several issues with 4.2.1 JB..

[stasnkoga]

jail broke iphone 4 a bout 8 months or so ago. jb 4.2.1 everything was great.
i purchased mywi and was using it via usb . again, all great.
of course wen i plugged it into my macbook pro it would sync. one day about 2 months ago it showed me an error messege :
" itune could not back up the iphone 'stankogas' iphone because the back up was corrupt or not compatible with the iphone,delete the backup for this iphone and try again"
so i would hit ok and it would finish syncing and everything would work fine. first question: what is this messege and how do i get rid of it ( delete corrupt backup etc...)?

anyways last week mywi wouldnt let me connect to internet. it happend once before and i unistalled and reinstalled it and it worked great again. not this time. in the mean time i have started using pdanet and it is working fine.

in the process of trying to solve the mywi problem i was going to restore my phone to stock and then re jailbreak it and then restore to a backup . dont ask me why because i was just trying anything at that point.
well i soon discovered that i had never backed my phone up for months ,so wen i did restore it it was taken back to a months old version of my jbroken phone. an inconvenience for sure, but not the end of the world.
at this point i have my phone pretty much how i want it againand want to back it up,but i get a that smae ' itunes could not restore because of corrupt backup etc" messege again...so i cant back it up at all.
second question : how can i back it up?

third question : im at 4.2.1...how do i go about upgrading to the highest possible OS with a stable and untethered Jailbreak?

i really need step by step instructions. if anybody can help me it would be great. thank you very much.

 

[liquidzoo]

Download TinyUmbrella (or the mac equivalent if there isn't a mac version) and hunt down the 4.3.3 ipsw on the interweb.

Make sure that you have the 4.3.3 shsh blob saved, either via cydia or use TinyUmbrella to download it.

Use TinyUmbrella's update server (there's a button for this, iirc) then, while holding shift, press restore in iTunes. Navigate to your 4.3.3 ipsw and it should install it just fine.

Warning: I've never done this, so I may have left out a step. Please research or wait for confirmation that my method works.

Also, for your backup issue: Find out via the iTunes Preferences screen where your backups are being saved to. I don't know the default location on my PC, let alone a Mac. Delete whatever is there and you should be able to back up your phone again just fine.