TPM cannot be found

Need the model number to answer -- XPS 9330, 7590, etc.  And most newer systems don't have a TPM -- they have Intel PTT technology.

@ejn63​ my Dell is Inspiron 3501, and I think my laptop should have TPM, when I start my laptop, BIOS shows up with "TPM device cannot be detected"

The system does not have a dedicated TPM.  The CPU is new enough that is will support Intel PTT (platform trust technology) -- you can go into setup and check to see if that's enabled. If the option does not appear, there are a couple of possibilities --you may need to reset the firmware (with the battery disconnected from the mainboard, hold the power button for 30 sec), or alternatively make sure the system was not originally sold in a part of the world where TPM/PTT technology is illegal.  It is illegal in large parts of the world.

Original post was to the XPS forum - moved to the correct Inspiron forum.

@ejn63​ sorry for my mistake. I have checked my BIOS and I couldn't find PTT option. My battery is non-removeable, so what should I do then? One more thing, I bought my laptop from a Dell store a year ago, so I'm sure it's legal. This issue has just happened for a week

You don't need to remove the battery.  Simply remove the base cover and disconnect the battery from the mainboard.   Then hold the power button for 30 sec.

Reassemble and check again.

System service manual is here

https://www.dell.com/support/product-details/en-us/product/inspiron-15-3520-laptop/resources/search

@ejn63​ It didn't work. Is there anything else I can do?