〜ものなら: if one could (but can't)

Says "if it were possible to do X" about something hard or impossible, often a wish or a challenge.

Usually potential verb (dictionary form) + ものなら, followed by a wish or 〜たい. Sounds like a longing ("if only I could"). It can also be a dare: やれるものならやってみろ ("try it if you can"). Do not confuse with 〜ようものなら, which warns of bad results.