Make and model TV stand?
Do you have the User Guide/Manual? There should be a parts list that shows the screw size(s) and quantities of each screw size.
Look for Screw type, diameter, and threads-per-inch information. May even be some part number as well.
If that information is not provided in the documentation or you do not have the assembly documentation then visit the manufacturer's website.
You may find an online (.pdf) copy of the assembly instructions and screw size information.
Or a Customer Support link to be used for requesting missing parts.