I am trying to paint a hood black in color and made some mistakes after a lot of work.
First the hood had some bondo in the corners with several dents on the top.
I sanded the hood down to the bare metal and got it smooth
After about a week I sprayed on my black base coat amd noticed there was still some dents in the top of the hood that needed to be fixed so I sanded them down and added some more filler and smoothed that out. I wet sanded the whole hood and sprayed the base coat again to get it all the same color.
I waited about 2 weeks and shot 2 coats of clearcoat on it and put it in the sun to dry
The next day there is cracks and shadows in the hood, and I am going to have to do it all over again because it looks like a idiot did the painting.
Will I have to sand the hood down to the bare metal again or can I sand the clearcoat with 400 grit and basecoat again?
This is my first paint job and I am doing it in the back yard. I was told that I waited to long before I clearcoated and that the paint got contamined.

You have all kinds of bad things going on there.

I sanded the hood down to the bare metal and got it smooth
After about a week I sprayed on my black base coat
Primer? before base

I wet sanded the whole hood and sprayed the base coat again to get it all the same color.
I waited about 2 weeks and shot 2 coats of clearcoat on it

Too long between coats. There is a "window" of time from the application of the base to spraying the Clear coat. It may vary slightly be brand, but you need to check it a follow the directions.

put it in the sun to dry


This is probably the biggest offender. The clear coat "dries" by a chemical reaction to the hardener, not evaporation. "The Sun" caused an even bigger reaction, exploding the whole thing
You have done accidentally everything you could against keeping the layers together. It has probably "de-laminated" (the cracking will turn to peeling).

The only safe thing is to strip the whole thing and start over. Follow the manifacturer's instructions about mixing, time between coats, etc.

I sprayed Valpar Primer after I had sanded it to the metal then wetsanded the primer then a basecoat.
Will I still need to sand it back to the metal?

I would say at least to the primer.

Sand it back down to primer at least, you have to get UNDER the cracks. Hopefully you can tell where they started.I would shoot a couple coats of primer then block sand. That will get rid of any imperfections. wipe it down, shoot the base(3 coats to get coverage)wait 30-45 min after last coat of base, then clear. You'll be able to tell in the first coat of primer you shoot whether the cracks are still there. you'll see them in the wet primer. just make sure you give yourself time to paint and clear in the same day.When you are done clearing, walk away and let it dry. then let it sit for a day or two and polish.

is the valspar primer for bare metal or did you spray etch primer first?

I told the paint dealer that I needed some primer that would cover bare metal and this Valspar is what he said I needed.
Thanks for all of the replays.I will start all over again