pro mini 5v 328

hi there,
I'm new to the arduino thing so i bought couple of promini (clones) to play around with but i could only upload 1 sketch (blink) but after that every time i try to upload a sketch i get this message
(avrdude: stk500_getsync(): not in sync: resp=0x00).
any help would be appreciated,

You will need to provide more information.

What USB to serial converter are you using?

How have you got the two connected?

Post a picture.

What operating system?

What version of the Arduino software?

Yes ;ChilliTronix say you need to give those details

also check proper board & ports being selected or not

i found the above problem occur when bootloader got crashed. The LED light either be stable or Keep flickering(Not like Blink program). frequency is faster

That means it's failing to communicate at all with the bootloader.

Check the simple stuff as others above have said.

Connect to ISP and check that the fuses are set correctly. 90% of the time, if this isn't a cockpit error, it's because the fuses aren't set to use the bootloader.

If they are, is the board very cheap and blue, not quite standard layout, with the words "Dswy Robot" on the back? If so, the board is wired wrong - there's a 0.1uf cap between AVCC and Reset, instead of AVCC and ground. Along one of the long edges, there's a row of 3 caps, 2 0.1uf ones, and one of the loading caps for the crystal. Remove the middle one (or move it over 1 pad, so it connects from one of it's original pads to the closer side of the cap for the crystal - happens to be the ground side). Frankly, once these boards are fixed, I prefer them over the standard layout because of the ISP header. Pre-fix, these boards behave as you describe, and sometimes reset themselves when doing analogRead(). While the chances you have the same board are slim, this is an example of the sorts of bizzare behavior you can see with the shoddy pro mini clones from ebay... Sometimes you have to fix them before they can be used.

hold reset-button pressed until 'uploading' shows up.