New Gmail layout

No. It's gone.

In June Google stated "Approximately 12 weeks after the general availability announcement in July, any users who’ve opted out of the new Gmail will be automatically migrated to the new experience, with no option to opt out".

It's now approximately 12 weeks later so all remaining users have been automatically migrated, and the old layout just is not available any more - unless Google change their mind, which is not likely.

As Bob Dylan once said : "For the times they are a-changin'."

Unfortunately, there's no way back to "classic" gmail. You'll have to get with the times.

Get with the times, or ask your IT helper to solve it for you.