The first thing I would do is create a full image of the disk. You do need a second hard drive with at least the same amount of storage available as your disk with RAW partition is large, then you need to access the disk from another operating system to clone the entire disk to a raw image. You can use HDDRawCopy on Windows or DD on Linux.
The first thing to always try is check the disk for physical errors with chkdsk, and also check for filesystem errors. It's also often helpful to scan the disk with GParted (you can get GParted live to boot from USB into Linux, it has DD too for cloning the disk).
There are two main ways to recover data. First is to try restoring the file table that contains the pointers and metadata for the actual data on the disk. This is the first method of data recovery to try.
If you feel ready to start recovering data I recommend TestDisk most.
With TestDisk you can first of all try recovering the partition table, and on top of that you can let TestDisk scan for a valid MFT to restore the actual file headers and "undelete" the missing data by restoring the partition headers to something readable by Windows again. You do need some experience to properly handle TestDisk as it gives very advanced control over your partitions and file table.
The second data recovery method is software that analyses the actual data on the disk without looking at the MFT. Things like Recuva and QPhotoRec can analyse the data and try to piece together fragmented data from a hard drive. This does mean the file attributes like the path (and thus also filename), dates and permissions are lost. The file extension can be and most of the time are automatically are determined from the magic key in the file header.