If you can generate the http request the button is making, then you'll have the data you want. If the button is not making any requests then the data is already there somewhere and you just need to find it and parse it out.
EDIT:
In your case it's submitting the form data to a redirect to the same page. for this you would include the form data in the request to the page and it would have the resulting data in the response. For example:
import requests
headers = {
'Origin': 'http://59.180.234.21:85',
'Accept-Encoding': 'gzip, deflate',
'Accept-Language': 'en-US,en;q=0.8',
'Upgrade-Insecure-Requests': '1',
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36',
'Content-Type': 'application/x-www-form-urlencoded',
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
'Cache-Control': 'max-age=0',
'Referer': 'http://59.180.234.21:85/index.aspx',
'Connection': 'keep-alive',
}
data = [
('__EVENTTARGET', ''),
('__EVENTARGUMENT', ''),
('__LASTFOCUS', ''),
('__VIEWSTATE', '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'),
('__EVENTVALIDATION', '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'),
('ddlDistrict', '165'),
('ddlPS', '11'),
('txtRegNo', '100'),
('ddlYear', '2011'),
('txRegFromDt', ''),
('txRegToDt', ''),
('txtCompNM', ''),
('btnSearch', 'Search'),
]
response = requests.post('http://59.180.234.21:85/index.aspx', headers=headers, data=data)
print(response.content)
>>> b'\r\n\r\n\r\n<!DOCTYPE html PUBLIC ...... FIR No.</a></td><td style="width:10%;"><a href="javascript:__doPostBack('DgRegist$ctl02$ctl03','')" style="color:Black;">Fir Year</a></td><td style="width:10%;">FIR Date</td><td style="width:15%;">\r\n View FIR\r\n </td>\r\n\t\t\t</tr><tr class="DataItemStyle ">\r\n\t\t\t\t<td>0100</td><td>2011</td><td>29-05-2011</td><td>\r\n <input type="image" name="DgRegist$ctl03$imgDelete" id="DgRegist_ctl03_imgDelete" src="Images/print.gif" ... ... \r\n</form>\r\n</body>\r\n</html>\r\n'