Laura, are you sure ribbon is in the proper guides and position, if they are, slam the carriage back and forth a few times to un stick the position er.
You didn't give a model but if it is a print wheel machine;
If both upper and lower case don't work it is a keyboard problem.
If it is just upper o lower case it is the print wheel.
DickyO
It is "unlikely" that the machine contains both English and Arabic languages...not enough room in the memory plus keytops would be different for the 2 languages.