One of the most common problems I get with printers is when a problem has occurred and the user has sent several documents to print and they simply get jammed up in the printer queue, meaning nothing else will print until this queue is cleared
To clear the queue
Windows 11 - Right click on the Start Menu button at the bottom of the screen, choose Run from the menu which appears, type control in the box and then click OK - then click View devices and printers in the Hardware and Sound section
Windows 10 - Type 'control' in the box down bottom left corner which says Type here to search, and then click Control Panel in the menu that appears - then click View devices and printers in the Hardware and Sound section
Windows 8 - Right click on the Start Menu button and choose Control Panel - then click View devices and printers in the Hardware and Sound section
Windows XP/Vista/7 - Click Start > Control Panel and select Printer or View devices and printers in the Hardware and Sound section
Windows will then show a list of all your installed printers as shown below
Windows XP/Vista/7 - If you double click the printer that has an error or jobs stuck in the print queue you will then receive the following dialog box listing all the jobs in the queue
Windows 8/10/11 - If you double click the printer that you are having problems with you will see the screen below - click where it says x document(s) in queue (as circled in red below)
You can then click Printer > Cancel All Documents
You will then usually need to restart your computer to complete the process and you should then be able to print again (unless of course you have error lights or a message on the printer, if so then there is a different fault with your printer which will need to be diagnosed further)
Printer Offline
Another thing to check if you printer is not printing is to make sure "Use Printer Offline" has not been accidentally checked in the above menu - see here for more detailed instructions.
Wireless
If your printer is connected via wireless rather than USB then also try restarting both the printer AND your wireless router as often restarting (turning off and back on) the wireless router will force the printer to reconnect solving most wireless printing problems.