I cannot open spreadsheet files and have no shortcut to start new files
Help the helper to help you and provide information.
OS = ? / Lib.O version number = ?
Which steps to you take and what was the result of each step?
A helper needs to understand all and often needs to make simulations to provide you with an answer.
1 Back up your data
2 Uninstall all of LIbre Office
3 Redownload the installer
4 Before reinstalling, compare the MD5 checksum of the downloaded file with the MD5 value obtained when you click on the Info link (and, if you tell us which version you download, and which operating system and OS version you use, in a subsequent question, we can provide specifics on exactly how to do that).
5 If, and only if, the MD5 checksum matches, then reinstall.