L led not working on arduino uno

If you press and release the reset button, you should see a few quick flashes on the L-LED. If you don't see those, the 328P is either damaged or has lost the bootloader. The latter can be fixed with a programmer or second Arduino used as a programmer.

If your Uno isn't a clone with CH340 you can try the Loop-Back Test Instructions to check if there is more damage to your board. If that test fails on a board with the atmega 16U2 (the chip closest to the USB port) you probably have damaged the board beyond repair.

If this is a school project and your board is beyond repair, you can maybe implement it in wokwi and hope that the teacher accepts that.

Although that often is true, you don't know for sure in my opinion. OP might very well have been working on the project for a month or more, was doing the finishing touches and blew up the board.