Welcome to Pixelation (aka Pixelopolis).
Too bad the thing that you lost so much stuff because of the hard-drive crash, though now you're ready to fill your harddrive up with other better art, now when you'll be improving

I like the pictures you posted: they're really nice. The rocks looks good and remind me of lava reef zone from sonic 3, though the grass you added to them doesn't seem to fit with the style. The piece of ground below the sprites looks great too, and also reminds me of sonic 3. The (small) sprites look good I think, though the left one seems to lack contrast, maybe. I think you could add more detail. Also, you can keep this in mind when shading:

Instead of just making the darker colors darker, like in #1, you can make them less saturated(more gray) and more red/blue/purple, like in #2, which can make the hues more interesting. About the mushroom, I think you could use another shade of green on the inside of the hat: it seems a little rough. Shouldn't the foot of the mushroom reach higher up into the mushroom before being stopped by the green stuff? On the moon/planet I see nothing wrong, but maybe you could have made it with less colors.
I really like your style and hope you will continue in pixelart and improving, and show them on pixelation. Good luck!