Are you unable to save as AI (with or without PDF compatibility), or as PDF, or what (some fonts are blocked from being embedded owing to licence restrictions)?
What happens (not), and which error message(s) do you get, if any?
It dosnt matter on saving format it doesnt work if i save like ai with or without PDF compatibility and also pdf and it doesnt work for font ARIAL and each other. The error massage is An unknown error has occurred.
You may try to look at Items 1) and 11) in Other options; corrupt fonts or font cashes.
For corrupt font(s), first look for the last font(s) installed.
It is worth mentioning that it/they may strike even without being used in the cocument.