Sometimes USB ports work, sometimes they don't

My USB ports work for some usb devices, i.e., I use a wireless mouse and the USB port works for that. puhave inserted my SanDisk for downloading audiobooks yesterday and it recognized it and it worked, but when I inserted my external harddrive so I could retrieve a file that got lost somehow, but the computer wouldn't even recognize it. It didn't give me any kind of message it just didn't do anything. I couldn't pull up the files, it wasn't listed in the explorer window, nothing. This is a new problem and I've tried to figure out what to do on
the internet, but my problem seems unique. Can anyone out there help me. I'm not a techie and all of this computer stuff boogles my mind sometimes, but with clear instructions in simpleton words, I can usually pull it off. Please help if you can. It is greatly appreciated.
Thanks in advance
dswapp

I use Windows 7
If you need other info, let me know exactly what it is.

hi, have you try plugging it into another computer to see if external hard drive works?

Thank you so much for your reply.I haven't as my technological knowledge is very limited. The weird thing about it is That some of my USB devices work are recognized and other devices are not that used to be recognized all the time. I'm wondering if there's something in the settings. I uninstalled all of the USB hosts in the device manager and restarted the computer following directions from various websites and I'm hoping that will work. I didn't have problems yesterday, but I didn't use very many devices. The worse of my problem is if my external hard drive won't connect.

oscer1 said:

hi, have you try plugging it into another computer to see if external hard drive works?

have you tried this