If a TPM device is listed in Device Manager but with an issue:
This guide should help you troubleshoot and hopefully resolve the TPM device not detected issue on your Dell Vostro 5568.
Outdated firmware can cause the hardware to "lose" the TPM module. Visit the Dell Support Drivers & Downloads page. Enter your to find the latest BIOS for the Vostro 5568
: Some users found success by removing the CR2032 coin cell battery for 30 seconds to fully reset the CMOS. Experts Exchange 4. Update Firmware and Drivers