Hell Sir, i have been studying china for the past 5 years. but i came back to Ethiopia

Hello Sir, i have been studying in china for the past 5 years. but i came back to Ethiopia because of COVID19 pandemic. Currently, as per the request of the school. i have registered online for continuing my study for 2020/2021 but my visa had been expired on 20 July 2020.So my question is in order to renew my X visa did u need any letter from my supervisor or the school?