No version of VP stops working. The trial or free releases have limitations but they, too, don't expire and can be 'test driven' at anytime, to see what's new.
You can always reinstall your old registered version. If you have lost the installer, go here. If you have lost your registration, go here.
Only one version can be installed at a time, so when you install a different release the old one gets kicked out.
Don't know why you cannot 'upload' your files. Do you mean that you cannot add them to the bin/timeline, or that you cannot export your project?
If the former, please take a minute to share a file or two that does this and someone here will check it out. Just upload the file/s to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.
Using Google Drive, if necessary change "restricted" to "anyone with link can view."