my mac will boot up but won't let me click on anything or open anything?????please help me

Is the keyboard plugged in? Does the mouse work?

We need more info. What does doing "About this Mac" from teh Apple menu say about your processor and Mac OS version.

Since your post appears under iMac-PPC, I take it that you are using a PowerPC (G4/G5) iMac in addition to your iPhone. You could try resetting the system management unit, followed by resetting PRAM. The procedure (only for a PPC Mac) is to remove all peripherals first, unplug the power cable from the back for about 20 seconds, then replug it while holding the power button down. This resets SMU. Pressing the power button again should power on the iMac.

To reset PRAM, immediately on powering on, press the Command+Option+P+R keys and keep them depressed till you hear the start up chime at least twice. To further reset all starting parameters, immediately after hearing the start up chime, shift to depressing the Command+Option+O+F keys till you get the Open Firmware input screen. There, input in sequence the following three commands:

reset-nvram

set-defaults

reset-all

This should hopefully set your machine to start and work normally again, but bear in mind what I've said appllies only to the PPC iMac. Resetting the start-up parameters for different models requires different procedures and you have not mentioned what model your Mac is and what OS you are running on it.

I'd like to repeat the need to make sure that yours is a PowerPC G5 iMac (my alternate machine is one I got in 2005) to use the procedure I mentioned. If your machine is different, you need to use the procedure specific to that model to reset the start-up parameters.

You say it just turns on, but is it actually booting? How far is it turning on? Just to a glowing screen? Grey apple? Boot scroll progress indicator? Booting to login window? Booting to account?

You need to provide a lot more detail. We only know what you tell us. Right now the only thing we know is it turns on (by that I understand you can press the power button and get some indication the machine is powering up) and that the keyboard and mouse work. Now if you can say the keyboard and mouse are working then clearly it isn't not letting you "do anything" because it must be doing something that tells you they are working.

I will re-ask the question, which operating system version is this computer running?

Mac OS X: Starting up in Safe Mode - http://support.apple.com/kb/HT1455

What is Safe Boot, Safe Mode? (Mac OS X) - http://support.apple.com/kb/HT1564

Safe Boot takes longer than normal startup - http://support.apple.com/kb/TS1884

Mac OS X 10.4, 10.5 - Computer shuts down during Safe Boot - http://support.apple.com/kb/TA24054

Safe boot mode runs a directory check command similar to that used by Disk Utility's repair. In OSX 10.4 and later it ignores some stored information (cache) that is normally read that speeds up the boot process, and it moves some caches to the trash. It also uses only System fonts and disables all Startup Items, third party items, and any Login Items. Networking and some video components may also be disabled.