Here's why:
* Missing Verb: It doesn't have a verb that describes the action being performed. "Try" is a verb, but it needs an object to complete the thought (e.g., "try what").
* Missing Object: It doesn't have an object to tell us what is being tried or what the comparison is to. "Like what" is missing.
To make it a sentence, you need to add those missing parts. Here are some examples:
* "Try it like this." (The object is implied by context.)
* "Try it like the recipe says." (The object is a specific action.)
* "Try it like it was the first time." (The object is a comparison.)