What is your Windows version and Service Pack?
Is your Windows 32-bit or 64-bit?
If the system used to work properly what do you think happened to it since the last time it did work properly?
Are you able to use System Restore to restore the system to a date/time prior to this incident?
Describe your antivirus/antimalware environment.
Is this similar to the error message you are seeing or is it not:
Look at this example where the dbghelp.dll file has zero bytes and then running sfc /scannow has fixed the problem.
If you open a Command Prompt as Administrator and execute the same commands describe exactly what you see or post a screen shot of what you see so we don't have to imagine what is happening:
Here are some instructions about how to include a screenshot in your post:
How to include a screenshot in your post
Did running sfc /scannow as Administrator replace the afflicted file or did it not?
Since the dbghelp.dll is a Windows file reinstalling your browsers will not replace it and it is not a good idea to simply delete the file although that made at least Chrome stop complaining about the file.
Instead of saying you were unable to deleted or replace the file tell us what happens and exactly what you see when you try to delete or replace the file. Screenshots would help.