I started using blender 3 days ago so I’m still a beginner at it.
I started sculpting everything was ok until I decided to render to see how it look and this happened.
It looks like you have a ton of overlapping, intersecting faces. You might have duplicated part of your base mesh in edit mode before you started sculpting, or you used the grab tool and folded this thing over on itself and flattened it out again after. There is no easy way to fix this short of manually deleting thousands of misplaced vertices in edit mode, then re-sculpting whatever you lose. You’d be better off to scrap this and start over more carefully. In dynamic topology sculpting you should always keep an eye on how dense your mesh is getting and decimate or reduce it from time to time when parts get to be more dense than they need to be. Use the Collapse Short Edges option at least some of the time.
It was just for testing the sculpting mode so it isn’t a big lost.
Thank for the tip. I will be more careful next time I use this mode.
If you set a draw brush at 0.00 strength with Collapse Short Edges on, that will effectively be a “reduce polygons” brush. When sculpting I periodically tidy up with this to prevent unnecessarily messy sculpts.
