A shopkeeper earns 20% profit on his goods. He lost 20% of his goods during a theft. What is his profit or loss percent?

4% loss

Let the total number of goods be 100 and CP of each good = Rs 1 

CP of total goods = Rs 100

SP of each good = Rs 1.2

Now, 20% of goods are lost. Then, 80 will be left.

Total sale = 1.2 x 80 = Rs 96

Loss = CP - SP = 100 - 96 = Rs 4

Loss % = 4%