Site Not Working After Reinstall.

My site was recently hacked. I deleted all files and replaced with clean with the exception of wp-config.php which I cleaned manually to remove injectd code.

I put all new files on server, My problem is I ran upgrade.php and it saysno upgrade needed but now I keep getting redirected to an install page ie mydomain/install.php.

I deleted install.php but now im getting 404 error as it says install page does not exist. Surely I dont need to go through the install process as the site is an existing one ?

Help would be appreciated