Is it correct, the use of look for + in?
I looked for in the list of countries...
If not which ones will be the alternatives?
Thanks in advance.
This specific construction is ungrammatical:
✘ I looked for in the list of countries.
It's a hybrid of two different grammatical constructions:
✔ I looked for something in the list of countries.
✔ I looked in the list of countries.
Here, you need to either add a noun or pronoun between for and in or you need to drop for.
It's also possible you could keep the exact wording you have, but then you'd have to add additional words to the start of the sentence:
✔ It's what I looked for in the list of countries.
There's an implied subject between for + in. If the implied subject exists outside of the sentence then yes it is acceptable, eg "I looked for differences in the list of countries..."
As an incorrect usage, it could be intended that 2 different directions are being used at the same time. "I looked for the list" means there is a list and you don't know where it is (and maybe that you intend to look in it for something). "I looked in the list" means you already have the list. "I looked for in the list" could be intended to mean you'll look in the list for something, AND you'll look around for a list, or vice versa.