Did a very silly thing a few nights ago. Went to download a utility and clicked on one of those download arrows that isnt the one you wanted. Ended up installing 7zip which I un-installed straight away. Next night on boot up PC did not boot up completely. Some start up programs were missing, few strange icons on desktop, explorer wont work at all, Chrome keeps says its going to close and Excel, Word etc will not work at all. Tried to do a system restore but all dates selected wont restore. Have run spy bot, malware bytes and Kaspersky on full scans and nothing major comes up. Have also run SFC - no changes came up
Tried to install hijackthis but now says windows installer system cannot be accessed.
Any ideas as to whats going on - Is it a virus or has my registry been trashed meaning a repair of some kind
thanks in advance for any help