What should I do if a specialist overwritten partitions when installing Windows 7?

Question

Windows

There were three partitions on the hard drive: a tiny one for the internal purposes of the system (about 100 MB), a partition with the system, and a partition with data.
When installing Windows 7, the specialist did something such that all sections "disappeared".
The system has not been installed.
Tell me the possible actions to restore the data partition.

Answer 1

Tyts

Answer 2

Since you did not install the OS yourself, it is better to contact a company that provides the "data recovery" service. The service is paid, but by independent actions you can easily aggravate the situation.

Answer 3

Boot from LiveCD and use testdisk. Be sure to take a sector-by-sector photo first.

Answer 4

And it was not an expert.