Much of the stuff came from Sweetwater, which lets you download PDFs for everything you ever bought there. Musician's Friend has no such feature, and I never created an account at Zzounds, so I'm going through old credit card statements for proof of purchase. The local music store was able to print receipts for recently-bought amplifiers and is digging out files for me on things I bought before they had a proper database.
Sadly, the company I bought my ADAMs from has gone out of business. I have tracked down one of its principals who now works for another store and emailed him to see if the owners still have sales records. Sheesh. Then there's the stuff I bought off Craigslist - those will be writeoffs.
Just trying to remember everything that was in my cord bag, and where I got them, is a daunting task. Pedals, stompboxes, a MIDI merger, microphone, gobs of cables.
Let this be a lesson to you all. Take photos of ALL your gear and serial numbers, dig out your receipts and stash all that information somewhere secure. Do it now.