I entered radio reset code for 2002 civic now the clock flashes and will not allow me to adjust it. How to solve this problem

Okay, I'm assuming that you were sucessful in resetting your radio code.
I'm also assuming that you have a CD player (which may not be the case).
The flashing clock also functions as an error code indicator. It should say something, indicating what the error is. You can't set the clock until the error is resolved (a disc stuck in the CD player, for example, on no disc in the CD when it's been told to play).
The procedure is as follows (which you probably know):
The audio system display usually shows the time when the ignition switch is in ACCESSORY (I) or ON (II). It shows the operation mode of the radio, cassette player, or optional CD player/changer when you operate them, then goes back to the time display after five seconds.
If an error occurs while operating the optional CD player or changer, the display will keep showing the error code and will not switch to the time display until the error is corrected. You can set the time only when the clock is displayed.
To set the hours, press the H (Preset 4) button while pressing the CLOCK (SCAN/RPT) button. Press and hold the H button until the hour advances to the desired time.
To set the minutes, press the M (Preset 5) button while pressing the CLOCK (SCAN/RPT) button. Press and hold the M button until the minutes numbers advance to the desired time.

If you don't have a CD player, or no error is showing in the clock read-out, leave a comment so I can investigate further.
Hope this helps you.