Furniture, Wood and Cabinetry Finishing - HELP! Sanded stain off the wood

i need help.

So my parents are getting new wood stairs put in. to save $500 we were going to stain them ourselves. so we used benite to prep it, stained it, and used this stuff called polycrylic to finish it. our stair guy said to roll 2 coats, sand and brush the last.

Here's the problem. There are spots where it got sanded down past the polycrylic, past the stain down to the wood.

Is there anything anyone knows of that we can to do to salvage it???

We tried to put more stain on but it wasn't taking it right away. i'm trying to leave it on for a while to see if it takes, but if any one has any ideas i would love some help. thanks!

Sand it ALL off. Restain and recoat.

When sanding between coats of polyurethane, all you're trying to do is rough up the surface so the next coat sticks better. This is very light sanding. You obviously were much too vigorous the first time around.

I agree that it sounds like you are sanding too vigorously. (you should be using 180 to 220 grit- anything lower is far too course!

Starting over is likely out of the question if the area you are talking about is small. If the stain won't absorb into the wood, it's likely because the poly has penetrated into the wood, sealing it, in effect. If the mark is small, you could try to get a touchup marker, which is like a magic marker, but they come in various woodtones. If you have a woodworking store (the type for hobbyists and craftsman) in your area, they should have them. Use the marker and continue with your poly.