One of my rabbits is always under my cabinet and I can't get him out of there. I have tried hiding up the gap so he can not get under there and provide more hides for him but he is always under there. what would be a good way to stop this as I have tried everything and am running out of ideas. He is also digging up the carpet is there a fool proof way of stopping this?
In my experience if you block off the area with something as simple as cardboard before the rabbit decides the place is nice, you can redirect them easily. Where we have cabinets/dressers that the rabbit can get under. I take out the bottom drawer and use a stapler to attach a piece of cardboard on the inside.
Once the rabbit has decided it is home, you will need a more substantial solution (i.e. the box I built under the bed (link below).
From your description it sounds like you have made multiple attempts to keep him out from under the cabinet, all of which have failed. This means you have taught him that, all he needs to do is work at it and can get back under the cabinet, which is true for anything not made of steel.
If this is the case you will need to un-teach him. You might move the cabinet out of his area for a time, but I am not sure how long it will take him to "forget" that is his favorite space. The lowest budget solution with the least impact to your living space is to get some concrete blocks and build a "foundation" for the cabinet to sit on. Make sure there is not an easy way for him to get in. From his perceptive, the space under the cabinet will have changed from an easy opening to a concrete wall.
In a similar issue we had, the laundry hampers/baskets were sitting on the floor. These have holes in the side, and Ruby would sometimes pull on the dirty clothes through the ventilation hole in the side. We moved the hampers out of her space for about 2 months, when we put them back in I had built a box about 12 inches high to place the hampers on. She can easily reach up to the hamper vent holes, but she doesn't. When she is hopping past there is a solid box that she sees, not the tempting clothes in the hamper. The old temptation is separated by time (2 months) and space (12 inches) and it's not a problem any more.
There are solutions for digging and under spaces in my answers to these two questions.