Sorry you had a rough time Rachel1992. Just remember that you DID get the glasses off him and it only took about 25mins. Result!
Until he has got the hang of the drop command try not to expect miracles. The best solution is to not let him get hold of contraband in the first place (NOT easy, I know). Everyone has to be made aware that they mustn't put something down where he can get it if they don't want it damaged. You will soon become hyper sensitive to possible issues. I have become so tuned in to possible contraband that I even caught myself thinking that someone on TV would need to pick up the shoes they had just kicked off!!
Here's what I know with Archie: Try not to think of treats as a bribe. Don't show him the treats and hold them near him when he has something. He will immediately know that you are trying to get it off him. That is the quickest way to make whatever it is turn into the highest value item possible. NOTHING will convince him to give it up. If he gets something, I walk away. I call him to ME. When he gives up the item, the treat is a REWARD.
For training I went through a routine of training every day, doing the various things we did at classes. Sit, stay, heel walk, lie down, etc. this got Archie I to training mode so he was very focused on me and his treats. To get him to give up stolen things (remember, he was a VERY aggressive guarder so I needed to work hard on this one) I taught him to wait in one room and then called him with a rattle of his biccie box. I made sure he would absolutely come running every time he heard it, rewarding each time, before I moved to the next stage. Then I introduced a bit of tuggy or fetch with a toy. If he let go of it during the game (rare) I would praise him hugely but I didn't have treats with me so his reward was getting the toy straight back. If he didn't drop it I just said "OK game over" and walked away. I then went to the kitchen and shook his box. I waited as long as it took but eventually he would appear. However, I didn't give him the biccie. I would say "no, no, fetch it" pointing to the door. He was really quick to pick up on the fact that he had to bring the item to get the reward. The second he let go I said drop, praised and treated. Lastly I said drop before he let go, once I thought he knew what it meant. We practised every day and it did take a long time but we got there.