Hello Warning occurred while using stm32cubeide and the c file was deleted. How do I restore files?

Which kind of warning ? ... without more details quite hard to help you ...

Have a look to your workspace <workspace>/.metadata/*.log ... did you get trace of something here ?

Which kind of file have you lost (100% end user custom file or some source generated by STM32CubeIDE) ? If generated file which one (file location & name please) ?

Which IDE version & operating system are you using ?

I fear no way to recover lost ... but cannot imagine you're working without source control management solution (GIT, SVN, ...) so here is way to get your file back.

You can right click the folder -> restore previous versions to see if Windows saved a copy. If not there, check the recycling bin. If not there, it's lost without a great deal of effort.