Don't know if virus: Laptop suddenly won't do anything?

It starts up and logs in as normal but then I can not open anything.

Browser will not open

Will not let me search the system from the right hand Windows 8 sidebar

Can not open any type of game or application

The internet symbol shows me as connected, even with internet turned off

My anti-virus does NOT open on start up or at all

I can not open the task manager

If I click on these things it shows the circle icon next yo the cursor then nothing happens

My computer is a Dell 15z with windows 8.1.

Thanks.