Can't re-enable Avast

I have Avast Pro and last night disabled it for an hour because it wasn’t allowing me to open pps extension files. Now I can’t get it back working. I know very little about computers but have looked through every single section and can’t figure out what’s wrong. When I open it up it has a box that says the computer is unsecured and to click “Fix Now” to start it back up. I click it, my computer asks if I requested to start the program, I click yes, it brings back the Avast window but nothing happens. There is also another message below the above one that says Avast has been stopped or is in an inconsistent state with an icon next to it that says “start program” but the same thing happens as above and I can’t get it to work again. Any suggestions?

Repair: Start as though you are uninstalling Avast! through Add/Remove Programs (or Programs/Features on newer OS) , but choose the “repair” option when it appears, then follow the presented steps.

Already rebooted the system? If not, do it and see if it solves the problem.
If it doesn’t solve it, try a repair of avast.
start > control panel > software avast > add/remove > choose repair.

I have Avast Pro and last night disabled it for an hour because it wasn't allowing me to open pps extension files.
Was there a reason given why these ppt files wouldn't open ???