You will get nowhere until you find out why your adsl light is flashing.
Leave your PC switched off and connect your modem as follows:
ADSL line from your filter to the modem and power line. Switch on if adsl light continues to flash after about 20 secs it is telling you that either your modem is faulty or your connection from your telephone socket is not right. Your modem should plug into a filter and the filter direct into your trlephone socket or extension lead whatever you are using. If you are using more than one filter in your line this could be the cause.