thanks for ur answer. I have already get my data back. Unfortunately，my desktop still doesn't work. it looks like I lost every disk(like desktop, Document, etc.. I can not put my new files in them). Only the cloud drive can store files. Do you know how to fix it? or Is it necessary to reinstall the system to solve this problem? For the resource problem, here is the link to that website: https://www.imymac.com/powermymac/uninstall-mysql-on-mac.html It looks like ok when you use English. however, if you transfer to another language (like Chinese), Sudo rm -rf /usr/local/mysql *. it will appear a space between SQL and *. like this: https://www.imymac.com/zh-CN/powermymac/uninstall-mysql-on-mac.html I didn't even check that command in Chinese. it is very dangerous!!!!!!! Thank you very much!!