The ribbon greys out once I enter the egual symbol in a cell to start a formula

Harun24HR I guess I did not explain it well. When the ribon greys out, it becomes unavailable and I can't use it anymore. Only if I delete the = symbol it becomes available. And it is happening across the whole excel on my computer. I am not able to format any cell in any of my worksheets. I have google about it and tried everything but there is no solution. I am thinking about deleting the software and re-installing to see if works. I thought that some one here would know what to do, but appears it is an issue that nobody know. And btw thank you so much for responding. I sincerely appreciate. I will give it one more day and then I will delete the app from my computer. Thank you again Harun24HR .