Unable to install/uninstall any software

Two days ago, I install the aplication "weather-util" to see what was this (I am a new Ubuntu user). And after that I try to remove it.

The message appears as follow:

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[i][i]emanuel@emanuel-ubuntu:~$ sudo apt-get remove weather-util
Password:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
weather-util
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
3 not fully installed or removed.
Need to get 0B/14.2kB of archives.
After unpacking 123kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 119519 files and directories currently installed.)
Removing weather-util ...
Traceback (most recent call last):
File "/usr/bin/pycentral", line 1394, in ?
main()
File "/usr/bin/pycentral", line 1388, in main
rv = action.run(global_options)
File "/usr/bin/pycentral", line 953, in run
runtimes = get_installed_runtimes(with_unsupported=True)
File "/usr/bin/pycentral", line 198, in get_installed_runtimes
default_version = pyversions.default_version(version_only=True)
File "/usr/share/pycentral-data/pyversions.py", line 130, in default_version
raise ValueError, "the symlink /usr/bin/python does not point to the python default version. It must be reset to point to %s" % debian_default
ValueError: the symlink /usr/bin/python does not point to the python default version. It must be reset to point to python2.5
dpkg: error processing weather-util (--remove):
subprocess pre-removal script returned error exit status 1
Traceback (most recent call last):
File "/usr/bin/pycentral", line 1394, in ?
main()
File "/usr/bin/pycentral", line 1388, in main
rv = action.run(global_options)
File "/usr/bin/pycentral", line 875, in run
runtimes = get_installed_runtimes()
File "/usr/bin/pycentral", line 198, in get_installed_runtimes
default_version = pyversions.default_version(version_only=True)
File "/usr/share/pycentral-data/pyversions.py", line 130, in default_version
raise ValueError, "the symlink /usr/bin/python does not point to the python default version. It must be reset to point to %s" % debian_default
ValueError: the symlink /usr/bin/python does not point to the python default version. It must be reset to point to python2.5
dpkg: error while cleaning up:
subprocess post-installation script returned error exit status 1
Errors were encountered while processing:
weather-util
E: Sub-process /usr/bin/dpkg returned an error code (1)
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From this time, after this error, I was unable to install or uninstall anything, even the upgrades.
The error is always the same.

Can anybody helps me?

Thanks

Emanuel