text instead of numbers

[cilruca]

Hi, I would like to receive some help. I developed the software used in my company with the use of excel and VBA and have been using it for over 14 years without problems. Suddenly, I noticed that in cells where a number with decimals is supposed to be introduced, the information is treated as if it was text rather than number. Obviously, cells with formulas that depend from it show error. Another computer in the office behaves normally.
What could be causing the problem? How do I solve it? I hate to have only one equipment running in the appropriate manner.
Thanks in advance

[AliGW]

What is different about the machine showing the error? Operating system? Version of Excel? Without detail, it's very hard to say.