if you say you can't for the life of you remember something, you mean that you cannot remember it at all.

I know I filed it somewhere but I can't for the life of me remember where.

• it's early days
• it's early days yet
• It's easy to be wise after the event.
• It's every man for himself.
• It's feeding time at the zoo!
• it's funeral
• it's high time
• It's just not cricket!
• It's just one of those things.
• It's just one thing after another!
• It's more than my job's worth.
• It's no good crying over spilt milk.
• It's no skin off my nose.
• it's no skin off nose
• it's no skin off your nose
• It's not cricket!
• It's not over until the fat lady sings.
• it's not rocket science
• it's no use
• It's no use crying over spilt milk.
• it's no wonder
• it's now or never
• It's now or never.
• it's one thing after another
• It's one thing after another!