SanDisk 1tb Extreme causing file explorer to not respond?

It sounds like the card is suffering from a hardware-level connection failure or a corrupted file system that the OS can't mount

1) The "Physical" Fix : SD cards have tiny copper contacts that oxidize. Use a rubber pencil eraser to gently rub the gold contacts on the back of the card until they are shiny. Wipe off any debris with a lint-free cloth and try again.

2) The "Clean" Command (Destructive)

If you don't care about the data and just want the card to work, use diskpart to wipe the partition table:

• Open Command Prompt as Admin.
• Type diskpart and press Enter.
• Type list disk (Identify which number is your 64GB card).
• Type select disk X (Replace X with your SD card's number—be careful here).
• Type clean.

If this succeeds, go back to Disk Management to initialize and format it as exFAT.

Thanks