Hello Sir, I have been working in China for the past 2 and half year, but I come back to Ethiopia

Hello Sir, I have been working in China for the past 2 and half year, but I come back too Ethiopia for vacation before COVID19 pandemic. Currently, the university and my boss requested to return back to work, and my work permit is valid until Aril 2022; however my resident permit had been expired on May9, 2020. So my question is in order to renew my R visa did you need any letter from the university or the boss?