Neither sentence is correct.
"Can you suggest a good English textbook for me? I have to study it myself."
You've misunderstood the present perfect grammar rule, where you would use "have studied". However, "have to" is an obligation and a completely different grammar rule. The base form of the verb is needed: "have to study".
There are a few grammar rules which use "have" differently, so be aware that one single rule doesn't apply to "have".