When you say you've recorded before and this wasn't a problem, do you mean like, recently, using the same computer? Or three years ago, with a different setup? In other words, this same gear that you know for sure works is now causing an out-of-sync problem?

It would be helpful to know what equipment you are using, especially the audio interface, as that is often where sync problems originate. Many users of this forum add that information to their signature, so everyone who is trying to help can see it.
 
Also, have you recorded a track with a metronome on it, or are you using Sonar's built-in metronome, which does not record?

Same computer, just not recorded in 3 months. Cakewalk UA-25 interface. Basically I just click record, hear the metronome, and record in time. When I play that back and listen with the metronome sounding the recorded part is now behind the click of the metronome. Up to date computer, Windows 8.1, 17, sonar xe producer. Just somehow something's different. I haven't used sonar since around June this year. Recently posted a problem with Midi + Audio in the forum and that problem was resolved. Not sure if I've changed something since then to create this problem I have.

a lot of times when tracks are out of sync from each other it's due to one of 2 things.
 
1) mismatch of sampling rate between audio card/interface and sonar.  if you have your audio card set to 44.1k for example (either in the audio card's software or on a switch on the audio card itself) and your project in sonar is set to 48k, then you will have sync problems.
 
2) using 2 different soundcards for playback and recording.  check your settings to see if you have the playback and recording timing masters both set to the UA-25.  if you have one of them (playback for example) set to the onboard soundcard or some other "soundcard device" listed in sonar (and thus listed in windows) then you will have problems with sync because you are not using the same clock for both devices.
 

Yes for sure check your Timing Master in the preferences Audio dialog and that Sonar is using the ASIO drivers for the UA -25 and not your on board sound card. 

Stumped, thanks for any help. Checked most of what was suggested by everyone here. I'm using the metronome on Sonar that's not recorded on a track. (Asked by Larry J.) Checked the timing master in preferences audio. Even tried creating another new project from beginning to see if that might work. Still getting the same thing. I can record original first track with metronome, then when played back, the metronome is now slightly out of sync with that first track during playback. Any other suggestions out there? Don't mean to be a nuisance ... just can't figure whatsup. I've recorded songs before on same computer, can't think of any changes I've made.

you didn't mention checking if there were discrepancies between the project sampling rate and the soundcard's sampling rate.
 
if you haven't done that, I suggest again that you do.  what is your projects' sampling rate?  on the back of the UA-25, there is a 3 position switch which can be set to 44.1, 48 or 96.  make sure that your sampling rate there is matching your project sampling rate.  I suspect it's set to 48 and your project is at 44.1 or the other way around.

Is your delayed audio 'out' by a fixed amount or does it get worse as the project plays?
 
My thinking is, if it's out by a fixed amount, it's a latency problem, if it gets worse over time then it's a sync problem.

Beagle, thanks for that suggestion. I did check the ua-25 and it's set at 44.1. In Sonar, the project shows (under the now time view), 44.1. So that's the same. I still feel it's a sync problem. Still working on it...thanks

Go into  views>tempo and check to see if your tempo map is at the same BPM.

Lynn, Checked out your suggestion. views/tempo ... tempo map same BPM's. Problem still exists ... but thanks anyway ...