For some reason I can't remember how to say "try to _" or "have to (must) _" in Japanese. How can I say this? Any variations you can include would be appreciated.
Try to ~
have to(must) ~
~なくては is often contracted to ~なくちゃ
~なければならない can also be contracted and have ならない elided to form "~なけりゃ" or "~なきゃ" which is used informally.
Some other grammar for "have to" that was not yet mentioned:
This means "it has been decided that 〜", but is often used as an indirect way to say that you have to do something (even if it's been decided by you).
These all basically mean "can't not do 〜" or "can't avoid doing 〜", although the double-negative may slightly lessen the "activeness" of having to do it.
Each one has its nuances of what types of situations in which it can be used, whereas the "basic" ones in @Flaw's answers aren't limited (much, if at all).
"Most Advanced" (mostly formal and/or written forms only. Not likely used in conversation)