Windows 7 - External HDD properly installed but not available in My Computer

Here's what happened..

My external hard drive is plugged in my computer and everything fine until I opened the recycle bin which become not responding in the instance i opened it. I tried ending its task on the task manager however It woudn't and the explorer.exe becomes not responding also. I tried ending the process and its process tree but still nothing happens so I tried to restart it. However restarting takes too long and seems forever so I turned the power off pulled the plug while it was restarting. Then I opened windows in safe mode and restart again to open it in normal mode. But I can't find the drives( I have two partitions (F: and G: ) corresponding to my external hard drive on my computer, the only present is (OS)C: then I tried restarting the pc again but i still can't find it. I tried uninstalling(under device manager) the driver and reinstalling it and it is successfully installed however it is still missing in my computer.

The external hard drive is plugged in my computer when the problem occur until I boot windows in normal mode after safe mode.

I also tried mountvol /n and mountvol /e but I didn't fix the problem.

My external hard drive is sata and I have a Windows 7 Home Premuim 64bit. On Disk Management, it is Unknown and unallocated and the icon has a red + sign.

Hope someone can help me fix this. Thanks in advance