If you'd like help diagnosing a problem I thing you need to provide some more information - system specs, some symptoms / history at least.
If you're happy to just try a clean start you could go to the following site and follow the directions (making sure of course that you've backed up any essential data / applications first, which of course you've been routinely doing anyway, yes?): https://www.microsoft.com/en-au/software-download/windows10startfresh