Write clean .net desktop app for user to sync local files to remote webserver for storage

i have php website like dropbox where user can sync local files w/desktop storage application to my server side php application depending on their chosen storage plan on the main site, but the desktop program is old and very outdated (.net 1.1),so it does not sync with the website/user account details properly so basically, i need a clean and simple desktop application that will allow website users to sync their local files to my domain/website via their desktop app, like other data backup services like dropbox, carbonite, acronis,etc . i awarded this project to another freelancer last week, who said he can have it done within 4 days, but he has been unrespomsive after tons of communication back and forth, so i am ready to award job to another who can complete the job within budget. im hoping to award to someone who may have a codebase in place for this, so maybe wont have to build from scratch and can cut down time to complete, since i have already lost time from previous developer. i have included screenshots of the current (outdated) .net desktop app. this will help get a visual of the functioning thats needed.