Problem with Permalink

Hello,

I already have a problem with my wordpress blog; When I changed my permalink option “default” to “Custom, specify below”, I had filled the “Custom structure” with a wrong URL, like “/http:/www…” Since, my blog does not work at all, and notify “500 Internal server error”.

I tried to resolve the problem, by deleting “htaccess” file with FtP client. So I could view my blog and login to the admin space, the I restored the permalink option to “default”. But my blog does not work again, (htaccess regenerated).

Could someone helps me about this problem or share some experiences about permalink troubles. Thank you