Will house insurance replace the whole roof when only some roof tiles are torn off due to wind damage?

No,, they only have to repair or replace the damage but it really depends on the type of policy you bought. If you bought the cheapest policy you could find than you probably don't have full replacement coverage.

If you only had some tiles or shingles blow off, then it does not matter what coverage you purchased, there is probably no need to replace the entire roof.