There is a big warning when you delete an account that says it will not be recoverable, so I suspect it is gone.
Have you had a look at your contract with the company? What does it say about the Analytics account? Some companies set them up incorrectly under their own accounts, so it is very hard to pass them on - and deleting them may be the only option.
You may have a case to pursue them for damages, but you will need to come up with a figure for the value of the damage that is reasonable. You may also have to prove they did it, as if they used your username and password, not their own admin account, they could claim you did it yourself.
Hopefully you have some copies of old reports with at least summary data as a baseline. |