Очистил фаил HOSTS .Что делать ?

Радоваться

Если у вас 7 и выше, то в этом файле нет рабочих строк. Если ниже, то рабочей там является только одна строчка, про localhost. Более того, путь к этому файлу настраивается в реестре.

Стандартный выглядит так:
#
# 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
....если напрягает что он пустой можешь это в него вписать и успокоится

А с какого бодуна Вы решили, что проблемы незахода в сайты находится в файле hosts, который, кстати, никак не должен быть пустым?

# 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
127.0.0.1 rad.msn.com
127.0.0.1 apps.skype.com

# This HOSTS file cured by Dr.Web Anti-rootkit API

Он немного отредактирован чтобы рекламу блочить в скайпе.
А так вот еще почитай http://skalolaskovy.ru/kill-viruses/245-hosts-repair

у всех он пустой

Смотря какая система. Варианты выше из последних Windows. А в XP должно быть
127.0.0.1 localhost

#
# 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

127.0.0.1
там напишите и сохраните