According to one of my mechanics that has had many a Camaro, this is a reoccuring problem with them. He told me NOT to use push pins to try to pin it back up, they fall out and are painful when you sit on them. He claims you can either rip it out or replace it. But if it is drooping, the material has stretched and it's next to impossible to get it to stay up.
Best of Luck,
〉 Answered on Jan 4th, 2007 by Amy Mattinat, Owner and Author at Auto Craftsmen Ltd
You may be able to take it to a place that does sunroofs and see if they can fix it. Depending on how much damage was done or what needs to be fixed, they may able to fix the one that is currently there.
The alternative is to buy a new headliner, which can be expensive. You will have to check on your individual model to see the pricing.
〉 Answered on Dec 27th, 2006 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines