Your Windows filesystem should be mounted in the /mnt
directory. This should include any extra or external drives you have connected.
user@hostname:~$ ls /mnt -la
total 0
drwxr-xr-x 1 root root 4096 May 17 23:13 .
drwxr-xr-x 1 root root 4096 May 17 23:13 ..
drwxrwxrwx 1 root root 4096 May 17 18:22 c
drwxrwxrwx 1 root root 4096 May 17 18:22 d
drwxrwxrwx 1 root root 512 May 17 18:22 e
If you wanted to get access to your Documents folder, you can find it at /mnt/c/Users/%username%/Documents/
If you would like to access your Linux files in Windows, check out this guide.