Let's say I have the LG Optimus ME, with CM9 ROM installed. I am now going to return this phone from where I bought it, and how do I restore it to the original Stock Rom. How would I do this without any backups (because I have none )?
Go to the XDA forums and find your phones subforum. Flash the stock rom, flash the stock recover and lock the bootloader if it has one. If you don't it will void your warranty and I highly doubt they will take your phone back. I own a Google Samsung Nexus S.