Help, forgot my password to my linksys router!!!!?

I reset the router, and can browse the web but its unsecure, I need to secure it. After putting 192.168.1.1 then the admin box pops up. I put admin defaut passwords, it doesnt accept it. I also then put a different password I made. It doesnt accept any password. Before I changed the admin password to a diferrent one, it use to work. Could it be a virus? I know the default is admin, and password is blank. Its not accepting any password. Please help.