When an error occurs with data sent to a printer, the printer might print a document containing pages of strange symbols, random letters or scrambled text. If the problem only occurs once and resolves on its own, you don't need to worry about it. If it happens repeatedly, you might have a problem with your printer cable, the printer software, the specific file you're trying to print or a font file.
Basic Troubleshooting Steps
As a first step, try rebooting both your computer and the printer. Some printers retain memory while off, so unplug the printer from the outlet and wait a couple minutes before reconnecting it. If the printer prints incorrectly again, try switching out the USB cable that connects it to your computer. Any USB cable with the same connectors will work -- you don't need one from the printer's manufacturer. If you connect your printer through a USB hub, connect it directly to your computer instead to rule out a hardware failure in the hub.
Drivers and Software
Printer drivers and software control print output, and a bug in either can cause garbled output. Installing drivers for the wrong printer model or for the wrong operating system version can also cause this problem. Visit the printer manufacturer's website and download the newest version for your printer model. If you already have the latest version, you can try reinstalling it anyway, as this will replace any damaged or corrupted files. Some manufacturers also offer an alternative or generic driver you can try if the regular driver has problems or won't work on your operating system.
Font and Document Problems
A damaged font file or text document on your computer can look correct on the screen but print incorrectly. Create a new document using a different font and print it as a test. If it works, change the font to the one you're having trouble with. If it still prints without trouble, the problem lies in the specific document that won't print correctly -- copy its text into a new document to work around the issue. Otherwise, if the font won't print in any document, set a lower resolution in the printer's properties. If the font still won't print correctly, delete it in the Fonts Control Panel and reinstall it from its original source.
Trouble Printing PDFs
You might also run into trouble printing certain fonts that appear in a PDF, especially on networked printers. Unlike with other document types, however, you can't edit PDF files using the Windows 8 Reader app or Adobe Reader. As a workaround, print from Adobe Reader, click "Advanced" on the Print window and choose "Print as Image." This method can cause text to look rough around the edges, but avoids problems with font files. Printing a PDF as an image takes several minutes, so only use the option when regular printing fails.
If your printer still won't print any fonts or documents after you've tried different cables and reinstalled the drivers, the printer itself might have hardware damage and require repair or replacement. To confirm this diagnosis, try printing the same document using a different printer.