First, you can try to ctc the MFGR, one way or the other, for a hand-out/pamphlet. I know they all write them. Perhaps they can email it to you or even point you to their WEB site for how-to instructions.
Here's a start: http://www.maintain-homerepairs.com/vinylsidingrepair.html
If you don't have any extra pieces, you can use one from the 'back' of the house, or something, to replace what you have that's damaged. You know, kinda 'switch-out' the 2 pieces (the good w/the bad.) Other than that, just hope that your style is still 'in style'.