Operation method
Open the computer, find the Sogou browser, click and enter the main page, as shown in the figure.
After entering, search the "official website of QQ recovery" and click to enter, as shown in the figure.
After entering, click "Restore QQ Group", as shown in the figure.
After opening, log in to your account and enter the next page, as shown in the figure.
After entering, you can see the group number of the QQ group you dropped out, as shown in the figure.