Write down brand name and serial number
First of all, you need to find the brand and model number of the appliance that you want to fix. The manufacturers name will easily be found on the front side of the appliance. However, you will have to look for the serial number at its back or the bottom. Write it down on a piece of paper.
Search on manufacturer’s website
You can then go to the manufacturer’s official website and enter the information in the manufacturer's internal search engine on their website. If the manufacturer still produces the appliance or a one similar to that, you will most likely find a downloadable manual online.
Contact customer support through website
Many companies also provide live support on their websites and you can talk to their representatives through that, providing them with the information related to your appliance and ask for its user manual. Most probably, they will provide you with a link where you can download the soft copy of the manual.
Contact customer support through phone call
Call the manufacturer's toll-free number. Locate their toll-free number on the machine or on the company's website. If they still have paper manuals, ask them to send you one.
Check out consumer and appliance information websites
General appliance websites like Appliance411 offer links to manufacturer websites and tips on where to find manuals of discontinued appliances. Some appliance repair sites also contain information on different brands and appliance models.
Research similar products
Find a manual for a comparable appliance made by another manufacturer and follow the instructions on it, making changes for minor variations on your appliance.