Hi there, you don't say at what educational level your project is at, so we could be talking about anything to a high school science fair to a doctorate in mechanical engineering, but not to worry, as there is help available online for both.
For ideas on a science fair project, visit sciencebuddies.org/science-fair-projects, which offers ideas at basic level ('machines in my toybox'), intermediate ('moving water with a screw pump') to advanced ('how to build a mechanical sunflower').
If you're looking for a doctorate level engineering project, then most academic institutions will provide a list of research projects for which students can apply, be it in the US or around the world. Try mechanical.final-year-projects or findaphd.com/search for engineering project titles.
YouTube is a good place to fish around for ideas, and several users have posted tips for mechanical engineering projects, such as we see in this film: