i'm trying to power my arduino uno project with a phone charger but it does not seem to work. it does power my arduino nano if i hook that one up. and the uno does work when i put the same usb in my pc as power source.
Any suggestions?
Do you have a multimeter to check the 5 volts? If not, now's a good time to get one! 
What's the current (mA) rating on the charger? Maybe it only has enough "juice" to trickle-charge a phone?
Are you powering a shield or anything else besides the Uno board?
Is it a plug-in or battery powered phone charger?
It's not unheardof for battery powered chargers to turn themselves off if the connected device doesn't draw enough current - the charger figures the device must be charged, so it should stop wasting battery power trying to charge it more... though this is more often an issue on more power efficient development boards.
It is a plug in one, no shield atached just some leds. i do have a multimeter so i will try that. but still it is weird that the nano does work but the uno doesn't. the uno does get power but it looks like the code changes because the light react totally different
How are you hooking it up the phone charger. They have miniB connectors.
I've got some of the ebay USB phone wall chargers. They seem to power up my arduinos ok.
Yep I don't see a newer phone charger having problems most are way over a amp and some are two amp output