Download an alternative one from the market? hancent, chompSMS, Go SMS are all good. Or, factory reset. I cannot help you further (and my advice may be wrong) because I am not familiar with that phone.
Also, please read the forum rules and look through the forum for your appropriate phone sub forum. This subforum (for Computers and IT) is not the appropriate place for you question. IF you were to post in the right place (or even an Android general place), you would find people who have your phone and know how to help. It would both expedite your answer and keep the forums organized--a win-win situation,
-Nkk