Yes, the shingles are ruined. In fact, many may be split or many may have even fallen off (and down) behind the siding. There was a LOT of vibration and hammering when the vinyl was installed.
Here's what I suggest. Get 2 estimates from 2-3 contractors. Ask them to estimate the Demolition and Installation (of the new shingles) separately. You can EASILY save some $$$ by doing the Demolition yourself. (Remember, though, that YOU may be responsible for the disposal of the 'old stuff'. Otherwise, talk to your selected Contractor about splitting the cost of a dumpster if he needs one too.) Anyways, DON'T tell him you're interested in doing the Demo work. Just tell him you want to see the cost of the Installation (which requires the 2 'jobs' to be written separately.) I'll be candid in that if you're asking if you can remove the old stuff, I have to assume you aren't handy enough to do the Installation too. That's why I'm suggesting the 2 bids. DO get 2 or 3 at least. Ask about the types of shingles and ask why Contractor 1 is more (or less, depending) than Contractor 2, and so on. This way, you can see why one Contractor is more (or less) than the other. Maybe it's because of the type of shingle? Maybe it's because one Contractor will 'seal' them? And so on.
My best to ya and hope this helps.
Jay J -Moderator