、。
If I were in your shoes, I wouldn't know what to do.
Literal
I [subject-が] your position [if-なら], how do good question not-understand probably.
君の立場なら ('if [it were] your position') is the conditional framing. どうしていいか is an embedded question ('what would be good to do'). 分からない with the final だろう adds modal uncertainty ('probably wouldn't know'). A common 'walk a mile in your shoes' consolation or empathy statement.