Please help me wuth this app (URGENT)

Hey, i accidentally updated this app on my computer last night and tried syncing into the iPhone and it's not compatible with anymore!! i have the iphone 2g so it has 3.1.3. what can i do to get the older version. please help me out.

P.S I downloaded a .ipa file of whoshere old version and tried install it with itune it said authorize the app purchase which wasn't purchased from account,So edited the .ipa file changed the account name still ask for authorize again annd again while syncing. I DONT HAVE A BACKUP EITHER. Then copied the .ipa file through open SSH and tried installing from installous but no luck its starts and closes automatically. Im still getting notification badges. Please please help me out i love this app and i dont afford a new phone or an ipod as i bought a new BB -_-. There should be a way.

What is the App's Name?

More info would help. Like, what is name of app? How is it listed in App Store? Do you have updated version, latest version?

I didn't understand a word of your PS but I too have an old iPhone with 3.1.3 on it. You could try contacting the developer directly and explain the situation, perhaps they will send you a copy of the last version that worked. In future be VERY careful updating apps, as this will inevitably happen to EVERY app you own (ie a future version won't work on your old iPhone/iOS 3.x).