First make sure that you do not have any bootable external media attached when starting up (Thumbdrive, SD card, Floppy disk, etc.).
Before using the nuclear option of decrypt/reencrypt. First try suspending BitLocker, rebooting, then resume BitLocker. If that doesn't work, then reset your PIN (https://help.bridgewater.edu/index.php?/Knowledgebase/Article/View/145/19/changing-the-bitlocker-pin). If those fail only then do you turn BitLocker Off/On. If this is a corporate laptop your IT department must do this.