How to restore the original iPhone font?

Okay so, I'm running iOS 4.1 in iPhone 3gs. It's been unlocked and jailbroken here on the Philippines so I can't really update its iOS on iTunes. Updated it before without the idea that it will make the phone locked again. Long story short. I searched on google if there's anything I can do to fake my iOS version so that I can download apps that requires higher iOS. And found one! Download and installed it right away. I was so happy that it worked and fooled App Store to think I'm really running the iOS 4.3.4. If I'm not mistaken. Then installed new fonts found on the internet. And applied it through Bytafont. Now, my problem is. When I restore it back to the original, it won't. I tried reinstalling Bytafont but still no luck. I'm stuck with the font I downloaded from the internet. Do you think it's because of the fake iOS? I want the default font back. I'm so stressed how to return it back to the original. Will someone please help me? :'( Thank you in advance! I really need it.

There's one thing you can do restore it to its 6 or the max for 3GS I thin it goes upto 6 so then you hv to rejailbreak and unlock it using evasi0n ( google it ) hope it helps

Cheers!
Ps make a backup first so you don't loose your data and contacts etc
Btw update it iOS by going into dfu mode ( YouTube it)