1958d wheat penny with major errors

How could this happen? and what type of error

Amazing! This one in a million error coin went 66 years without anyone recognizing it until in landed in your hands. How much do you think it's worth?

I don’t know what happened 

Collar error.  https://www.ngccoin.com/news/article/9216/mint-error-coin-chronicles-partial-collars/

Nice find, but not worth much.

 Also has some ghosting on the back. More on one side from a the collar issue. 

If you do an Advanced Search on eBay using the terms Lincoln collar error, (Sold Items only) you will see a number of sales.  

I am seeing some similar coins sold for $5 - $10, so you won't get rich, but on the other hand, that's a 50,000% return on investment 😀.