If the EndNote tab is missing in Word, particularly if you have had it previously and it has disappeared after Word crashed, chances are Word has disabled it.

To re-enable it:

Click Word’s ‘Office button’ (the circular button at the top)

then select ‘Word Options’ (bottom right of the options that appear)

then ‘Add-ins’ from the options on the left

then at the bottom of the box choose to Manage ‘Disabled Items’

then select EndNote (if it’s there) and click ‘Enable’.

Hopefully this should resolve the problem.