Hi @AlexNikitina,
Was this a space that you created? If it was, you can see the list of spaces owned by your account if you click on your name in the upper right, then click on your Account in the panel that opens. From there, you should be able to click on Spaces in the header to see the list of spaces owned by your account.
If this is space you did not create, or you don't see it in that list, you may need to talk to whoever originally invited you to regain access.
Hope that helps!
Mel