I can't type on Excel! Lock? I did not protect or use password

[JOHNNY M MILLER]

iN THE PAST I USUALLY TYPE ON EXCEL BUT SOMEHOW IT LOCKED THIS MORNING
YESTERDAY IT WORKED OK BUT NOT TODAY SOMETHING IS WRONG. FROM WHAT HELP SAID
IT HAS TO DO WITH PROTECTION, CELL, PASSWORD
I NEVER USE WHO DID IT? GHOST?

 

[Mike Hall \(MS-MVP\)]

Is it a trial version?.. did it come pre-installed?..