My External Hard drive, is having problems going on

Hello,

I own a 2TB Seagate External HD, and i've been having this problem for a long time. Every time I try to plug the plug wire to the External, it wont light up until I try to plug it multiple times, also a recent problem which worries me even more is that when I plug it, it light up, I can feel the HD spinning but it wont boot on my laptop and eventually the light will go off, it eventually works after trying to plug it multiple times again but i'm getting worried. How can I fix this? I can't afford to simply buy another HD and I rely on that to save most of my files. I also only use this occasionally, Any help is appreciated.