huhu,help me,my w550i can't play music!

i had my mobile (w550i) felt into the water last night,immediately i took it out and use the WC paper to dry the cover.In the morning,i took it to the Repair shop,they opened,dried,and it had been ok,until 1 hours ago!hix,i can't open the walkman music player,everytime i open it,it freeze!Only take the battery out and get it.I've tried master reset but has no result!
But when i play song step by step in the Manager File Menu,it's Ok!
I think this is software fault.Should i reinstall my software?and how?
sorry because i'm newbie ^^
hope to get reply soon
thanks :x

The best way to flash your phone is XS++...use the "searchfunction" and you'll find some Downloads...

But i would take it to a service point or send it to SE...i think its not a softwareproblem...but we'll see

it's a software problem,i trust.Because when i play it in File manager,it's good.That shows that the hadware is ok,too.So the problem must be software,you know.
could someone show me how to resolve this???what's boring Sony is when it can't play music fluently,hix >.<

reflash-it with xs++ or phone xs , it`s FREE , and it will work good if you`l unlock it again too :)

ac ac,if i reflash it,i have unlock it,too???huhu,it's so difficult to me,hix.I've never ever done that before.
hiiii,but,however,today,i try to master reset it finally,and,it's fantastic,the walkman player is ok!!!!!!!! ^^
but i still don't know what was happen to my mobile???
anyway,thank everybody :x

FIRST!: find ssw for w550. (working ssw...) Don't flash if you find only: w550_r2e_dcu.49r.ssw (65kb big) IT DOESN'T WORKS!!! And FSX don't works too on w550. Be careful! (I don't know no1 who did it with that ssw...)

I know my english is very bad...