Accidents happen but there are solutions, don't worry. If the Raspberry Pi OS taskbar and icons, The following are two options for for all Raspberry Pi boards and the Pi 400.
Terminal commands - open a new terminal window (via SSH or similar if you have no terminal icon) and enter the following commands:
rm -r /home/pi/.config/lxpanel
Reinstall Raspberry Pi OS - When in doubt, reinstall! Just download the Raspberry Pi imager tool and follow these instructions: https://www.raspberrypi.org/software/
Please note: this will erase any files or settings