reporting service add feature does not work

HI All,

I am using sql server 2008 R2 SP2 I want to start reporting service but after trubleshooting i am not able to start service then i uninstalled the reporting feature and then want to add feature again to configure report server but this is not work giving me the error :"instanace name is already in use " Please help me to short out this problem.

Regards,

pawan Singh

Thanks