I have a Triumph that is rooted and flashed with CM7. I would like to learn how to flash roms and unroot so what better way to learn then to flash back to stock, then back again. But I do have some questions, I am very new to all this so bear with me. I also have titanium backup ( the pro version). What is a nandroid backup and Im sure I did a backup before I rooted and flashed but Im not sure what file it is. These are the files I have on my pc. Under Clockworkmod-backup,under Clock Works Mod Recovery-recovery-cwm-5.0.2.6-triumph, Recovery Stock Backup-(there are 2 files in this folder)-CM7-TG-reloaded-20111230(which is a zipp file), and recoverystock.img.bu(which is a disc image file). Can someone please help me out and tell me what these files are. I dont want to use the wrong file. Also, does someone have step by step directions to return this phone back to stock. I take it I have to flash the stock rom and restore the nandroid backup of the OS then?? Please help me with this. Thank you in advance for all you help and advice.