Hi every one,
I'm fairly new to excel and am pretty much self taught and learning as i go, I've got a sheet i use at work to track multiple people's productivity and have ran into an issue where people are going back and changing numbers for hours previous and was wondering if there is any way to format the cells to lock after a specified time? Thanks in advance for any help.

or if it is simpler is there away to lock a cell if say the value of 0 was input?