Accidently deleted the complete history on Firefox and now I have problems getting into certain websites?

[DunbarPappy®ϟϟ]

Changed;
Clear cookies & cache.
It's easy to do with "CCleaner". Freeware.
http://www.piriform.com/ccleaner
Run that at least 1X/week.

Try "MalwareBytes" to start cleaning up your system:
http://www.malwarebytes.org/
(free version has no "real-time" shield)

Modify Firefox:
FIREFOX: Tools> Options> Privacy> top drop slot set to "Firefox will use custom settings..."> Check 'Accept Cookies from sites' &
â–ºUn-Check 'Accept 3rd Party cookies'.
â–ºGet "AdBlock Plus" http://ca.answers.yahoo.com/question/ind...202AA4cljP
( ☛AdBlock must now be modified: http://www.ghacks.net/2013/07/31/how-to-...-blocking/ )