I reached the airport

[suniljain]

I reached the airport at 4, however, her flight had departed at 2.

Can I use "took off" instead of "departed"?

 

[Raymott]

No, you can use "had taken off" instead of "had departed."
"Had took off" is wrong.

 

[tzfujimino]

suniljain, I think your sentence should be "I reached the airport at 4, but the flight had departed ..." or "I reached the airport at 4. However, the flight had departed ..."