Re: What can i do?
There should be a stamped HULL ID on the starboard side of the transom within two inches of the top of the transom, gunwale, or hull/deck joint, whichever is lowest. Its stamped into the metal / fiberglass so it can't fade.
Once you have that you are all set. If you really can't find anything to identify the boat, like 57 mentioned, call DNR and explain the situation - they will definitely be able to tell you what to do. I had a similar situation where the DNR actually issued me a new Hull ID as well as a number for my homemade trailer and I was responsible for installing it on the boat.