Rating calculation problem Firstly I got 1018 rating last year. Then next tournament deducted 25 and my FIDE rating became zero. 


Then I faced next tournament opponent 03 players 1352, 1255 and 1174 respectively. All 03 games I lost.
Then I faced next tournament opponent 03 players 1288, 1315 and 1153 respectively. I won 1315 rated game and other 02 lost.
Then I faced next tournament opponent 02 players 1227 and 1334 respectively. I won 0.5 with draw 1334 rated player and other one lost.


Then I already got 1.5 points, but still my FIDE rating is showing 0. I want to know how many games I need to play and win to again take my FIDE rating.
please check Ekanayake E M Anindu Rehan Fide ID is 29909279


OK, so this is your playing record -

2017-10
1754    0
1155    0
1371    0   

2017-11
1112    0   

2018-04 (1018)
1286    0
1079    0
1018    1
1318    0
1067    1
1090    0   

2018-05 (1018 - 25.2 -> 0)
1418    0
1332    0
1221    0
1292    0   

2018-10
1352    0
1255    0
1174    0   

2018-11
1288    0
1315    1
1153    0   

2019-02
1227    0
1334    0.5   

Let's go back and check the FIDE rating regulations.


  6.1 If an unrated player scores zero in his first tournament, his score and that of his opponents against him are disregarded. 
  Otherwise if an unrated player has played rated games, then this
  result is included in computing his overall rating.


In your first two tournaments you scored zero points so these are not used in any rating calculations.

You got your first rating of 1018 in the April 2018 list after a tournament in the previous month. Let's see how the calculation works. First the relevant parts of rating regulations:


  8.2 Determining the Rating 'Ru' in a given event of a previously unrated player.
  8.21 If an unrated player scores zero in his first event his score is disregarded.    First determine the average rating of his competition
  'Rc'.
  (a) In a Swiss or Team tournament: this is simply the average
  rating of his opponents.    ...
  8.24 If he scores less than 50% in a Swiss or team tournament:  Ru = Ra + dp


2018-04 (1018)
1286    0
1079    0
1018    1
1318    0
1067    1
1090    0
Sum of opponents' ratings = 6858
Average of opponents' ratings = Rc = 6858 / 6 = 1143
You scored 2/6 which is 33%. Hence:
Fractional score = p = .33,
Then I look up in table 8.1a from the rating regulations to find 'dp'
dp = -125 so new rating = 1143 - 125 = 1018   

Now if we repeat the calculation for what your current rating would be we again throw away the first two tournaments (2017-10 and 2017-11) and use all the tournaments since then.

We get:
Total sum of opponents' ratings = 6858 + 5263 + 3781 + 3756 + 2561 = 22219
Total games = 18
Rc = 22219 / 18 = 1234.39
p = 3.5/18 x 100 = 19.4%
dp = -251 (looking up in table 8.1a for p=0.19)
So new rating = 1234.39 - 251 = 983.39   

This is less than 1000 so you are recorded as unrated.

If your fractional score had been 0.21 (i.e. you scored 4 / 18) then dp according to table 8.1a would be -230.4 and you would have had a rating of 1004.

So, basically you fell short by one draw. If you continue winning one game in three against similar opposition then you should make it.