"you Need To Format The HDD Before You Can Use It" HDD ADATA CH94

I have a problem. Yesterday i took my HDD, and copied some movies from my friends laptop. I copied around 19 GB worth of data on it. Then removed that HDD and placed it aside. Then remembered a few minutes later that i wanted to copy something else, so i plugged it in and suddenly i got "Need to format drive G: before you use it". I thought oh shit that error again. Because before i used to get that, but then i plug it in another computer (usually my own) and boom it works again. But now, i got back home and plugged it in but still i get the same message. I tried it on my brother's computer and my sisters as well. I still get the same error.

What i think what the problem might be is that the boot sector might be corrupted. Anyone has an idea of how to fix this damn problem? There is no way i will format my HDD, cause i have over 250 GB worth of data that i cannot afford to loose again (i had another HDD in the past that got fried - god knows how - and i lost 350 something GB that i was not able to recover back). The data is not backed up since my shitty computer cannot contain all of the info.