I can't type numbers into excel cells -- using 2013

[nrc2015]

I've stuggled with this for 3 days and have looked through all related posts I can bring up through search. I have found several replies that suggested fixes--it appears there are many recently who are dealing with this issue. I've worked through all of them but nothing has worked. I even copied the spreadsheet to a new blank workbook. I was trying to type in 8.25. It let me type in the 8 digit, but then wouldn't let me type anymore. Instead it jumps up to the next row--same thing it was doing in the original spreadsheet. Has anyone had experience working through this problem?