Messenger Sounds Gone after installing and uninstaling beta 8 Urge

Hi, I have a problem.
I've tried Messenger live Beta 8, unistalled it cause I prefer 7.5,
and then reinstalled 7.5 and the problem started. I 've no sound on
messenger for example contact online, new message, new mail, etc, no sounds
at all. And even the sound scheme disappeared from Tools- Options- Alerts
and Sounds- Sounds, etc... When I go there I no longer have the option MSN
messenger like before... So I've tried to repair messenger (several times
should I say...) and nothing... Them I uninstaled 7.5, did a full system
repair, install msn 7.5 again and still nothing, no sounds... So I've
unistalled 7.5 again, tried msn 6 and guess what...no sounds!
I'm using 7.5 again but without sounds... If somebody haves a solution
please help, cause there are other discussions with the same problem but no
replies...
Thank you!!!!
PatrÃ*cia