in comments to the answer you took the code from someone says ShellExecuteEx doesn't post its STDOUT back to the originating shell. so you will not see "I am root now", even though the code is probably working fine.
instead of printing something, try writing to a file:
import os
import sys
import win32com.shell.shell as shell
ASADMIN = 'asadmin'
if sys.argv[-1] != ASADMIN:
script = os.path.abspath(sys.argv[0])
params = ' '.join([script] + sys.argv[1:] + [ASADMIN])
shell.ShellExecuteEx(lpVerb='runas', lpFile=sys.executable, lpParameters=params)
sys.exit(0)
with open("somefilename.txt", "w") as out:
print >> out, "i am root"
and then look in the file.