cant change MC version for some reason

I cant use the current launcher of mc. It doesnt let me change the version. I tried multiple times trying to fix the problem, but I couldnt. Heres what appears
[17:48:01 INFO]: Minecraft Launcher 1.6.73-j (through bootstrap 5) started on windows...
[17:48:01 INFO]: Current time is May 31, 2017 5:48:01 PM
[17:48:01 INFO]: System.getProperty('os.name') == 'Windows 10'
[17:48:01 INFO]: System.getProperty('os.version') == '10.0'
[17:48:01 INFO]: System.getProperty('os.arch') == 'x86'
[17:48:01 INFO]: System.getProperty('java.version') == '1.8.0_131'
[17:48:01 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'
[17:48:01 INFO]: System.getProperty('sun.arch.data.model') == '32'
[17:48:01 INFO]: proxy == DIRECT
[17:48:01 INFO]: JFX is already initialized
[17:48:01 INFO]: Refreshing local version list...
[17:48:01 INFO]: Refreshing remote version list...
[17:48:02 INFO]: Refresh complete.
[17:48:02 INFO]: Loaded 1 profile(s); selected '_Block'
[17:48:02 INFO]: Refreshing auth...
[17:48:02 INFO]: Logging in with access token