it's been 4 days since my finger got slamed by a big rock 1st finger in my left hand and there's like a red color under my nail and the question is that can i still play my guitar or no if no i would be so sad to hear that and it still hurt a bit
You tell us if you can play guitar. If your finger is functioning near 100%, and it doesn't hurt too much to play, then you can play.

If you can't bend it cause it's so swollen or every time you press down a string lightly and it feels like Thor is smashing your finger with his hammer, then no, you can't play.
PRS SE Custom 24
Jackson DKA7
Gibson Explorer
MESA/Boogie Express 5:25

Dunlop Cry Baby Classic
VOX Joe Satriani Ice 9 OD Pedal
VOX Joe Satriani Time Machine Delay Pedal
Ernie Ball Strings
V Picks
If it hurts, then dont play
Quote by CoreysMonster
Why, my pasty danish cracker, I believe you've got it!
Only you know the answer to that.

I fractured my 3rd finger on my left hand. Played through pain for about 6 months.

Its down to you.
i had something similar happen. you can train your other fingers for a while. that's one benefit, sorta. you probably wont be able to play everything that you want but with three working digits you can train them to do basic chords. i hope you have a speedy recovery, not playing sucks
"My vocation is more in composition really than anything else - building up harmonies using the guitar, orchestrating the guitar like an army, a guitar army." Jimmy Page, god
i tore all the ligaments in my fretting wrist, and for a month it was agony to play.

leave it if your in pain, and wait till you can play for a small amount of time before you begin to feel pain, and build upon that amount of time through small blocks of practise.

worked for me
Guitar - The true Religion