Help!font file on phone corrupted?

I turned on my phone one day and all the fonts were messed up. All letters were in a different font and only certain letters would show up. What's wrong and how do I fix it? your help will be much appreciated. Thanks

first we need to know what phone are you using and we need more information regarding its' CID. Read here : Flash your phone and How to apply or remove patch using SETool 2 Lite - Top Sony Forums
and post the identify log here

ChipID:9900,EMP protocol:0301
PHONE IS RED RETAIL PRODUCT
FLASH CID detected:52
Speed:921600
Flash ID check:2019
Flash props sent ok
OTP LOCKED:1 CID:49 PAF:1 IMEI:35170801343514 CERT:RED
FLASH CID:52 COLOR:RED

Model:K800i
MAPP CXC article: R1CF001 prgCXC1250215_HONG_KONG_WI
MAPP CXC version: R1CF001
Language Package:HONG_KONG
CDA article: CDA102511/85
CDA version: R7A
Default article: cxc1250490
Default version: R1CF001

Operator: 000-00

Elapsed:8 secs.