While hundreds of new hair and beauty products enter the market every year: sometimes the oldest solutions are still the best.

This sentence:

While hundreds of new hair and beauty products enter the market every year: sometimes the oldest solutions are still the best.

Is incorrect.

Explanation:

The reasons this sentence is incorrect are two. First of all the colon is used incorrectly. Because it is used to provide specific information that falls into a category that is produced by the sentence before the colons. However, in our case we don't only receive an example of that category's elements. But an explanation. And explanations shouldn't be introduced by colons. They should be followed by them, making it very clear the following elements are part of the category presented.

the main character of "the secret life of walter mitty" retreats into a false pretense as a means escape from his mundane reality -- this is a flagrant issue seen in societies abroad, typically found in young adults and it is robbing our youths of their childhood.

explanation:

a thesis -- a well developed, formal thesis is required to be one sentence long. there are many themes in "the secret life of walter mitty" and i had resolved to give you one of the simpler ones while still honing it with class.