Session Drummer ...Dear God please help....what has gone wrong

Please dont say i have to start my song from scratch.    So.... i recorded a song, mixed it..saved it. Fine.   Tonight i saw a listing on TAXI which really suited my song and it has to be in by tomorrow. So i went to open the song just to check it sounded ok.  I got dll errors saying SD2 couldn't be found.  I recently upgraded to X3 so I'm actually using SD3 now. But the project opens and all instruments play fine....but no drums.  Oh great.  The meter (on the drums track) is moving up and down but it's like its on mute.  I usually do a "save as" when i'm recording a song in case something goes wrong. So i opened one of the earlier versions of the song and the same issue arose with the drums.       I did a rescan of the VST folder and it seemed to find all the plug ins but still no sound from the drums.    Now here's the weird part.  I opened a different song and the drums are fine.   So the problem seems to be with the song and not with the DAW.  I opened the inspector and checked the input / output settings of the working song and made sure the "faulty" song has the same settings but no joy.   If i open Session Drummer, as in, open the window which shows the drum kit, and hit a drum or cymbal, you can see cymbal moving but no sound.  I dont have the drums going to a bus by the way so it's not a case of the bus being muted. 
Please tell me someone has seen this before and I dont have re-do the song from scratch :(    Thanks guys. 

After you get that sorted out, you might find this article useful about how to merge the SD2 content from previous Sonar versions with SD3.

X3e is the latest update and I highly recommend installing it. Alex would too.
 
http://forum.cakewalk.com...vailable-m3009206.aspx

I know this is silly, but is there a kit loaded into the drums? Did you try loading a different kit. I had issues when I upgraded ( 8.5 to X3)  where my old pre sets had to be re made from scratch. 

Hi lads.  No you're not being silly at all Sock and in fact you would think that this is the problem...but the dang kit is loaded.  I have the songs backed up so if i have to reload Sonar then so be it.
Just an extra little bit of info guys.  I thought that all other songs were working.  I was wrong.  One song is fine the others all have the same problem.   The song that works is my latest song.  I cant say for certain...but...here is what i think is happening.      My latest song used Session drummer 3 and its working fine.   The others were recorded before i upgraded so they would have been done on SD2.    One of the guys put up a post further up on this discussion on merging SD2 with SD3.   I'll give that a shot and see how it goes.   At this stage, I guess i should be trying to get all my songs to use SD3.         

To elaborate, when I upgraded, same as you from SD2 to SD3, the kit would show in the pre set menu but  there was no sound. 
Did you try loading a fresh new kit? this is not clear if you have tried this yet as that is what I had to do and then all was good.  

Your project should still have MIDI data in the track, even if SD3 appears not to be "loading." Simply loading a kit with SD3 will give those MIDI notes something to "fire." When you open that project in X3e (please be sure to upgrade to the latest patch), immediately save it with a new name (with X3 in the title), and work from there.

Some slight progress guys.  Added in a new SD3 as suggested and added in a drum kit.  opened the "drum kit" window and clicked on a couple of drums...horray...sound.  Copied the original track into the new drum kit and then deleted the old "faulty" SD.   I now have drums again.  Sadly, I dont have the same sound.  I'll have to go through each drum and load a drum sound i like.  I hope i dont have to do this with the other songs but i have an awful feeling that is what I will have to do  :(      If i could create a  nice sounding kit and save it , that would be handy. 
But hey, at least I've made a bit of progress so thank y'all for the great tips.  Wonder what the hell went wrong in the first place.   This all started with an error saying the SD2 plug was not detected when i opened Sonar the other night.   You would think that once I scanned the VST folder it would have fixed the issue.   Even after installing the X3e update and rescanning it didnt fix the issue. 

I did Alex.  At first i just did a scan but as you suggested earlier, i then did the reset.   The problem is definitely coming from the old SD2 from what i can see.   The only song not affected was a new one I did after the upgrade.  I'll keep digging to see if there is a way to fix all songs in one go.  Although the steps i took to fix this song worked, it's a lot of work.  I dont suppose there is any point in me replacing one of the faulty songs with a back up version from my external hard drive?  Something tells me its not the song that is faulty but something either with sonar or SD2.

I would think you would want to do the reset prior to the full re-scan, but that's just my view on it, and I do not know if that would correct your situation or not.
 
Bob Bone

Yes i want to go through that article Mr Anderton linked for sharing those two SD's.   I'll close off this post now and thank you all very much for your replies and help.  There have been some very good ideas here and I appreciate your time and help guys.   Just in closing Sock, i should note, the songs didn't go funny right after the upgrade.  The songs were opening fine for quite a while now following the upgrade. I'm not great at mixing so these songs did need more work anyway so it's probably not the end of the world.  My main nightmare was the fact that a song which was nicely mixed and ready to go was at risk.  And like i say, i wanted to send that one into TAXI and the deadline was yesterday.  Fortunately, I had already an MP3 made of it so i got the song sent in.
Hopefully, once i replace all the SD2 drums with SD3 going forward I should be ok.  I'll create a custom kit once I pick out a nice snare, kick etc and make a note of where these are saved.  At least then i can simply reload that kit as you do with your Birch kit.    Thnaks guys.  Have a great weekend.