A HDD that had a fall isn't very promising.
Is the 3.86 GB unallocated on a 1T disk drive on another partition?
Is your disk a Legacy - MBR or a UEFI - GPT?
Get another backup into gear as soon as possible; your present backup drive may [or hopefully may not] have been compromised. I think the best thing to do is make brand new full images of your OS partition and your data partition onto a new backup drive. Then, do whatever the hard-drive fixit gurus recommend to thoroughly test and either pass or fail your first backup drive [the one that was accidentally dropped].
My Computer
At a glance
Windows 7 Professional 64-bitDesktop i5; Acers i5 & i7desktop 16GB; 1 Acer 8GB & 1 Acer 16GB
Computer type
PC/Desktop
Computer Manufacturer/Model Number
Antec desktop; Acer Aspire laptops
OS
Windows 7 Professional 64-bit
CPU
Desktop i5; Acers i5 & i7
Memory
desktop 16GB; 1 Acer 8GB & 1 Acer 16GB
Hard Drives
1TB split into 2 equal partitions [OS and data] usable by RJS
Internet Speed
AT&T DSL
Browser
FF, GChrome, msIE
Other Info
Windows 7 Firewall, Emsisoft AM/AV, MSE [scan-only], SpywareBlaster, Ruiware/BillP combine