Good day,
A couple of days ago decided to upgrade one of the important Rar files, and tried to open winrar issued the following error: "CRC error: Unable to extract RAR files and appearing a message saying mismatch in size."
How to be, what to do, I do not know.
I tried to open a 7-zip, also no success.

using the command line version of RAR, you can type rar /? and look at options. there should be options to "fix" a file or try extracting in different ways. have a look, maybe something salvageable is in your file.

maybe you have the data somewhere else?

I already had such issue a few times.
From your description of the issue, I'm not sure if you can see the folders and files or if the problem comes when you try extracting the files.

If you cannot open the archive:

1) Make sure that the archive is a unique ".rar" and not one part of a multi-files archive (.part1.rar, .part2.rar).

2) Make sure that the size of the archive or of each part is correct, especially if you downloaded it; check the exact number of bytes it should have.

3) Try to open the archive with 7z Manager. (7-zip GUI)
If the archive is password-protected, make sure that you entered the correct password.
If the password contains special characters like ^, @, ~, a.s.o. keep in mind that such characters sometimes require the next character to be entered; if such character is the last one, a trick is adding one more character after the password it and erase it before validating the entered password.

If you can open the archive but have the errors when you try to extract the files:

1) Extract smaller parts of the folder tree. If necessary create the large folders manually and drag-drop each sub-folder one by one. This way, you can recursively identify which corrupted file make the extraction impossible.

2) Make sure that you have enough free space on your C:\ drive (or Operating System drive) for the archive to be uncompressed. The extraction creates some temporary files before copying them to the chosen destination, so even if you extract the files to another drive (eg. D:) you need enough free space on C: to extract everything.

I hope this helps.