If you compile your .Net Core Web application two dlls are generated in the bin folder.
e.g. WebApplication.dll and WebApplication.Views.dll
WebApplication.dll contains the *.cs file whereas contains the *.cshtml files.
You could use a decompiler tool like dotPeek from JetBrains
dotPeek: Free .NET Decompiler & Assembly Browser by JetBrains[
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Then you can open your dll files with this tool in order to see the source code.
The source code may not look exactly like the code you have written but can give you an idea about how it was written.
A better idea for the future would be to not only store your source code on your computer but somewhere else as well. (Google Drive, GitHub etc.)
If e.g. your hard drive crashes or your house is burning down you will have the same problem again...