If you’ve jailbroken your iPod touch or iPhone 4S running on iOS 5/5.0.1 and your screen has shrunk down to 1/4 of its size, don’t despair because there’s a fix for it.
All you need to do to resolve the 1/4 screen issue is to
-Install SBSettings from your Cydia
-Launch the app and tap on ‘Safe Mode‘
If all else fails connect device to computer. Open Fun-Box, if you need to download it just google it. Start deleting the last app or tweak you installed. After you delete the problem you think. Reboot
If nothing above fixed your problem, your SOL, RESTORE. Thats all is left. Hope this helped. Leave a comment and let me know how it goes.