This is commonly caused by a problem with preferences.
Navigate to the folder below. Then click on the version of acrobat you are using (DC, X, XI....), The either from there move the preferences folder to another location or delete it entirely. Restart Acrobat and the problem should be resolved.
(To get here the quickest hold down the windows key then hit R, Paste the folder path below into the box)
C:\Users\%Username%\AppData\Roaming\Adobe\Acrobat\