Gaming Consoles & PCs Lost Serial Numbers or Registration Keys If you lose a game's serial number, you may be able to get it back by Courtney Marchelletta Writer Courtney Marchelletta is a former freelance contributor to Lifewire. gaming enthusiast, and sim player who proves video games aren't just for guys. our editorial process Courtney Marchelletta Updated on December 02, 2019 Robert Daly/Getty Images Consoles & PCs Xbox Buyer's Guide Tweet Share Email One of the first things you do when installing a game on your computer is enter a serial number or key code. Without it, you can't activate the game. If you are positive you have lost your serial number or key code you aren't completely out of luck—yet. There are a couple of methods you can use to locate it. Check Your Computer's Registry There's a good chance you can find a stored serial number in the Windows Registry, so check to see if the key code is still there. Even if you uninstalled the game, an entry with the serial number may still be in the registry. Be careful not to delete any entries while in the registry, or you may have problems getting your other programs to run. Go to Start and click Run. Type in regedit and click OK to open the registry. Search for the game's title using CTRL+F, and click F3 to continue the search if the title doesn't show up on the first page of results. Look in the data column for a long string of numbers and letters that looks like a serial number. Write it down or copy and save it. Download Key Finder Software If you don't find the serial number in the registry, try using one of the many free key finders. This should solve your problem if you had the game installed on the computer at some point. Tips for Storing Serial Numbers Be prepared for the next time you lose a serial number by trying one of these tips for saving your serial numbers. Keep your keys in a text file, and always keep the newest version backed up.Write the key on the CD, if the game came on one.Keep a notebook of keys.Write it in the manual if the game has one.Send an email to yourself with the key and save that email in a folder just for saving serial numbers and keys.