In any situation when you have your data lost the number one rule you should follow is not to write any information to the hard drive that was damaged.
If you accidentally deleted an existing partition, leave the space blank and do not create any new partition.
If the files you need were previously deleted from the recycling bin, first of all try not to save any new files to the hard drive. In other way there is a big risk to copy new data over necessary information, as any files that had been erased by the hard drive are actually just marked as having been deleted. Every time system needs to store additional data on the hard drive it copies new files over those that had been marked as 'deleted'. In that case recovering new files will most probably end unsuccessfully.
The same rule works for partitions. Partition information only presents a way how the operating system must address the space that is available on the drive. If the partition will be wiped out the information it contained also must be gone. But this is actually not true. Though the operating system cannot see any partition information and thus any data that it contains, that does not mean your data was really deleted - you just can't see it. But data-recovery programs can.
When I had a similar situation I decided to test the drive integrity with FDISK. In order to do that the program writes patterns of data to different areas. Though eventually one of the partitions was missed and a boot sector was destroyed so the XP installation had became unbootable, almost all the necessary information was recovered.
But if you want to fully restore the information that has been lost, avoid writing any new data to the drive. In case your hard drive has only one partition and it became damaged the best thing to do is obviously to transfer the drive to another computer, preferably with the same file system that your partition used.
Transferring your hard drive to another computer has dual benefit as it allows you not only to prevent accidental rewriting of the data but also to explore its file structure via the simplest explorer that is currently available.
In case your operating system files have been erased or damaged but the information about partition is still valid Windows will not boot anyway. But your data can still be read with another operating system.
I know it as once there was an accident when one of the two XP partitions on my disk was mangled and after moving the HDD to another computer it became fully accessible again.
If there is no opportunity to transfer your damaged drive to another computer you should not immediately re-install your operating system. Before that you can try using one of the software tools that will allow you to boot an alternative OS on your computer and help you to recover necessary files.
But you should remember that no new data must be written on a damaged hard drive, and if you have a single HDD it becomes much more difficult to avoid such a situation, as most of the recovery programs need a place to copy the data it recovered. If such an occasion has happened to you it is much better to install a new HDD with a new operating system or find a computer to transfer the damaged hard drive to.
In both cases you achieve two advantages. First of all, now your lost data may be accessed in a normal way via Windows File Explorer. This is true if the partition information hasn't been modified as the operating system must 'see' the logical drives.
Secondly, you may be sure that no necessary data will be irreversibly lost as now you have a separate hard drive that can be used for putting data, which was recovered by any program you prefer, onto it.