You are your company's SolidWorks Workgroup PDM administrator. Every time you install a new service pack of SolidWorks, your SWPDM VaultAdmin tool is missing. To correct the issue, you can browse to your SolidWorksExplorer.msi file in the swexplorer folder of the SolidWorks service pack download. Run this msi file and modify your SolidWorks Explorer install. You will want to do a custom install and pick SolidWorks Workgroup PDM VaultAdmin.
To prevent this from happening the next time you install a service pack using the Installation Manager, you can pick which products to upgrade.