Something may have messed with your hosts file. That is a system file that will redirect any IP address to another, hard coded. Check these instructions to view/edit the system hosts file. There may be something in there causing you problems.
Beginner Geek: How To Edit Your Hosts File
This is what a plain vanilla hosts file should look like. This is straight off my desktop, just upgraded to 11099.
It is in this folder.... C:\Windows\System32\drivers\etc. Filename is "hosts". You can open it with Notepad.
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# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# ::1 localhost