My name is Jon. I will do my best to help. It sounds like one of the pins has dropped out of it's cylinder. See if you can use a small pic or straightened paperclip to push the pin (Gold Piece) back up into it's cylinder. While holding your pin in place with the pic, see if you can get the key to insert into the lock and remove your pic. If you can get the key into the lock, do not remove the key or he pin will drop back down into the same position. Let me know how this works.
If you can gold pin to disappear, see if you can insert a small piece of wax to hold the pin up while you remove the tool. this should leave you enough room to insert the key. The wax will just push out of the way when the key is inserted.
Sentry may be able to send you another key. However, at this point, I would just have a locksmith replace the cylinder of the lock. When he does this,he will give you new keys for your safe. I am sorry I could not be more help. It is always a challenge a challenge to visualize exactly what a customer has going on with an item and to tell them how to fix it over the internet. Do you need any help finding a locksmith in your area?
No problem.. If I can help in any way, please let me know.