Go to ~/Library/Preferences. Move the com.apple.Safari.plist file from the Preferences folder to the Desktop.
Quit then relaunch Safari to test. If that helped, move the .plist file to the Trash.
~ (Tilde) character represents your Home folder.
If that didn't work, quit Safari. Open a Finder window select your Home folder in the Sidebar on the left. Then open the Library folder, then the Caches folder, then the com.apple.Safari folder. Move the cache.db file from the com.apple.Safari folder to the Trash. Relaunch Safari.