I am new to C#, but I have been working on a inventory and price checking program for a few days now. But when I tried to continue working on it today the file would not open. I got the error message “These files could not be found and will not be loaded.” If anyone has some advice which would help me be able to access it again I would really appreciate it.

Have you renamed a folder? If in source control (git) have you changed the branch. Both crazy obvious I know, but we all do crazy occasionally.
It sounds like the .sln file has an invalid path to the .csproj file. Check the .sln and make sure it has the correct path from the .sln file to the .csproj
Is it possible windows defender or another AV is blocking access?

Worst case scenario, make a new solution and use the “Add > Existing File” (shift + alt + a) to solution function to re-add all your source files. Hopefully you haven’t configured too many file properties (e.g. Build Action: Embedded Resource, etc.) so this won’t be too painful.

Otherwise, this may be a good lesson to encourage you to start using Version Control like git + source tree. Here you could have simply done the commands:

And it would have dropped back to your latest saved commit (last snapshot of source files). In the case where you have a catastrophic failure of your local environment (someone drops your laptop into the sea), you can simply make a pull request to your remote repository and be back on your feet in seconds.

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