Yes, wash it, give it some love man, previously I explained why it is important to give your bike a good wash once in awhile, after all, did you not wash your tank and carbs to get it running again.
This is a '99 750SS we are talking about, the most underrated and most reliable Ducati ever, they don't just break by standing around, unless the OP is omitting something, like a developing condition prior to parking it for a few years, there will be no reason to start any kind of serious dismantle, not the kind that you need a manual for anyhow.
Get the very basics sorted first, OP have not even tested for spark yet.
Batteries that are not healthy can wreck havoc with these bikes and a new battery does not guarantee anything unless you verify (I replaced the starter solenoid on mine just to learn that my new-ish battery was no good).
Yes I'm sure that this forum will get the OP sorted, but he need to cover the basics first and he need to communicate on his progress, and yes, who knows, maybe while washing his bike he may just notice that connection hanging loose somewhere.