Hi, I accidently deleted the central administration of sharepoint instead of deleting other site. i dont know how can i recover back with out effecting the current sites?

NEVER post the same post to more than one forum. I have deleted the duplicate you sent ca 10 minutes after this one directly to Setup...Admin. Please don't do this again. It wastes everyones time having duplicates. (Moderator) FAQ sites: (SP 2010) http://wssv4faq.mindsharp.com; (v3) http://wssv3faq.mindsharp.com and (WSS 2.0) http://wssv2faq.mindsharp.com Complete Book Lists (incl. foreign language) on each site.

Try re-running your configuration wizard. You should be able to take the defaults and have it rebuild the site. I think that it will do an iisreset at the end of the wizard, so you will have a short downtime at the end, but its normally not more than 5-10 seconds depending on your server speed.