My Passport not showing up on MAC

My family and I had just recently come back from vacationing in Florida. Where we visited Disney World, Universal Studios, etc. There we had taken pictures and recorded videos of our stay. Well during our trip i transferred all pictures to my laptop which is a Toshiba Satellite because at the time I didn’t have a portable hard drive.  When we had gotten home from our trip I transferred the pictures from my laptop to my newly purchased “My Passport”.  I transferred the images, everything was fine. Went to MAC and wanted to transfer images from my MAC (main computer) to the hard drive. It wouldn’t allow me to. After *properly* ejecting and plugging it back in to see if there is anything else I could do to get the files from my MAC to the hard drive, I had read up somewhere that in order to do so I have to save the data that is on the hard drive on the MAC. Erase the hard drive’s settings/data. Reformat it to MAC, and transfer all the files. 
My hard drive isn’t showing up at ALLL now. After trying and trying finally an icon pops up on the desktop. as “Untitled”.
There’s no yellow USB icon anymore labelled “My Passport” but a silver USB with what looks like a meter and it’s labelled as “Untitled”
This is only the second time I’ve ever used this, I’m just wondering what the **bleep** is the problem. Shouldn’t I be able to transfer items to the hard drive without it being Backup? 

If the drive was originally formatted for Windows then it will be read only on a Mac. Try this on the Mac NTFS-3G . I don’t know about Macs so I’m not sure on what’s best to get it recgnized again.