If you are using Safari ...
From the Safari menu bar click Safari > Reset Safari
Select the top six boxes then click Reset.
Quit and relaunch Safari to test.
If that didn't help, open a Finder window. From the Finder menu bar click Go > Go to Folder
Type or copy paste the following:
Click Go then move the Cache.db file to the Trash.
Quit and relaunch Safari.
See if that worked ...