Problem while typing capital word F

I am having a problem while typing the capital word “F”. If i press the button shift+f or capslock on and the type f also, the word capital F is not coming, but instead a question mark in the upside down is coming. and this is the case with only the capital word F and not with other words, but if i type small f, it is coming as normal, the problem is with only capital wod getting typed F.
So how can i solve this issue…??

Thank you…

Please, give LO version and OS

Did you already look into the ‘Replace’ tab of AutoCorrect’ > ‘AutoCorrect Options’ for the language actually chosen for your document? If you there type an F under ‘Replace’, do you get something under ‘With’ ? Probably the inverted question mark U+00BF “¿”?