[HTC One SV] :
What??? You do not have a backup? Always, ALWAYS, make a backup of your device BEFORE you start changing things. Oh man... Well, I have a backup loaded on my dropbox account but it is for K2_CL so that one is useless to you. You need to check out [MENTION=3142060]old.splatterhand[/MENTION] index. There may be one available on there to download (if the link isn't dead). If the backup was done from CWM then you will need CWM to restore. If it was done with TWRP you will need TWRP to restore (very important). [MENTION=5089229]russellvone[/MENTION] 'may' have one sitting off to the side. However, I'm gonna give you a class right here and right now; for you and others reading this.

When your phone is fresh and you HAVE NOT made any changes to it but have future plans to do so then this will go as follows:

-- Unlock bootloader (if not done already)

-- Grab a custom recovery (either CWM or TWRP)

-- Boot the custom recovery (NOT FLASH)

fastboot boot customrecovery.img

-- This will boot the custom recovery on to your device WITHOUT overwriting your stock recovery.img

-- Once it is booted you will want to make a FULL backup of your device (a backup can be as large as one gig so make sure you have space)

-- Once backup is completed then save it on your PC and you can optionally leave it on your ext sdcard which I do myself personally

-- Now and ONLY now you can go ahead and flash a custom recovery.img

fastboot flash recovery customrecovery.img

-- (EXAMPLE)(Restoring from backups with different OS version - this goes with ICS also); If you are S-On, and your backup is 4.1.2 but you upgrade to 4.2.2 and wish to restore back to 4.1.2 then you WILL have to take the backed up boot.img from your backup and flash it using fastboot because the kernels are different and may cause conflict with your system partition. This is due to the fact that you ARE S-On and therefore cannot flash a boot.img unless it is done so with fastboot so simply restoring and not flashing that boot.img in your backup will leave you still using the previous boot.img and NOT the one from your backup. (just rename the backup boot image to boot.img)

fastboot flash boot boot.img

-- (EXAMPLE); If you are S-On and are on 4.1.2 and restoring with a 4.1.2 backup then you DO NOT need to flash your boot.img using fastboot as stated above because your 4.1.2 kernel is still intact (unless you wiped it out)(this goes with 4.2.2 and ICS as well).

-- If you are S-Off then neither of those two instructions mentioned above pertains to you - just restore with your backup and all will be ok.

-- At this point, go ahead and start debloating your device, flashing roms if it is suited for your device, changing your CID, or anything else you have plans to do.

BUT NEVER EVER EVER EVER EVER EVER, make ANY changes to your device UNTIL you make that backup first. To do otherwise is simply suicidal and can place you in a sticky situation which would have you relying on others to assist. Now, having others to assist is not wrong and can lead to great ideas and even solutions, but always be prepared to take the challenge for yourself first if it ever comes down to it before having to go to someone else.

THE END :)

---------- Post added at 01:22 PM ---------- Previous post was at 01:02 PM ----------

To relock your bootloader is:

fastboot oem lock

If you are S-Off then see my signature below for other approaches which may be more beneficial.

---------- Post added at 01:32 PM ---------- Previous post was at 01:22 PM ----------

Do not relock your bootloader until after you have restored your device. Once you do, relock it and accept the OTA from your system update. If you are S-Off then it is ok to leave the bootloader unlocked.

---------- Post added at 01:44 PM ---------- Previous post was at 01:32 PM ----------

Update:

You can also use a backup from a higher OS version (if never upgraded before)(otherwise this step is pointless). Example would be you currently being on 4.1.2 and have not yet upgraded but are about to use a 4.2.2 backup. This is possible but will require you to flash the firmware.zip that can be found in the 4.2.2 OTA.

fastboot oem rebootRUU

-- this will boot you in to RUU mode. Next:

fastboot flash zip firmware.zip