Hello
@lloydroyle123 , and welcome to the Vaping Underground forums!
Oh, that is bad luck! I looked with Google, and cannot find parts anywhere. You can try to take it to your hardware store, and see if you can find a short screw that will work.
In vaping, it is SO important to have several devices, for back up. These things Do happen, and it is good to have something to fall back upon. Your tank looks like a very common design, a good source for inexpensive tanks is this website:
www.vapingcheap.com
Please let us know if there is any other way to be of help!