It seems like i bricked my arduino uno 
Its not detected on pc my arduino mega is detected by pc but when I upload code it says avrdude not in sync
Is my arduino mega is briked too??
CAN I BURN BOOTLOADER ON ARDUINO UNO USING ARDUINO MEGA OR VICE VERSA
any help would be greatly appreciated thank you
Burn bootloader cannot help you of the board is not detected on an uno/nano/mega*. A board that was working, but is no longer detecting has suffered a hardware failure of the usb-serial adapter (or usb cable or port - be sure to try a different port and a known working usb cable - shoddy, unreliable usb cables are very common, these cables have high failure rates during use from normal flexing of the cable, as well as high doa rates). Trying to fix it by bootloading it makes as much sense as changing the tires on your car when it wont start.
A board which is getting a sync error on upload could, in very rare circumstances, have had the bootloader corrupted (this will always happen if you connect an ISP programmer and do "upload using programmer", which erases the bootloader, but is otherwise almost unheard of, assuming the board previously worked (cheap cloneshave been known to ship without the bootloader installed, though this is rare). Sync errors are much more likely to be wrong port/board selected, or (on uno/nano/promini/mega) external hardware connected to pins 0, 1 or reset, or a hardware failure which cannot be fixed without replacing the failed part.
A working Arduino can be used to bootload another Arduino, but it must work - you need to be able to upload Arduino as ISP to it.