Today, I was applying for FPSC online and mistakenly I entered wrong date of birth. I submitted the form completely.
I reedited the date of birth as FPSC gives chance to edit application before last date. Again it saved the wrong birth day. Now again, it is not editing any more and saying that you have edited it maximum number of times.

Please let me know what to do now?

Contact Fpsc, you can do it on phone or by an email.. Hopefully , they will solve your issue. Tell them exact issue that you had. This link may help.lot of times people get this type of problem. So, it will be solved in Shaa Allah.
http://www.cssforum.com.pk/off-topic...ying-fpsc.html

And you can see contact details of Fpsc at their site. Basically you will have to contact their Islamabad Head office and then they will guide you about the procedure from now on. There are more chances that they will solve it on call or you will have to write an application to Fpsc.
I have just copy pasted whole contact numbers and mails given at their site ,below:

Lahore:
31-Civic Centre, Mustafa Town,
Wahdat Road,Lahore
Ph42-99260201
For address map, click here

Islamabad (Headquarter):
Federal Public Service Commission,
Agha Khan Road, Sector F 5/1,
Islamabad.
Ph: 051-9205075 (25 lines)
Ph: 051-111-000-248
Ph: 051-9212427
Ph: 051-9212423
Ph: 051-9212425
Fax: 051-9213386
Email: fpsc@fpsc.gov.pk

Karachi:
H.M.2 Bath Island,Karachi
Ph: 021-9250926

Peshawar:
Plot No.29, Behind Rehman Medical Complex,
Sector B-2, Phase-V, Hayatabad, Peshawar
Ph: 091-9217337

Quetta:
No.758/A/A-2, Sharah Samungli,
Jinnah Town, Quetta.
Ph81-9202955

Multan:
House No.7, Pakistan Street, Shalimar Colony,
Near Northern Bypass Metro Bus Station ,Multan
Ph: 061-9330145

Sukkur:
Bungalow No.B-41,
Professor Co-Operative Housing Society,
Shikarpur Road,Sukkur.
Ph/Fax: 071-5630510

DI Khan:
House No.30, Shami Road, D.I.Khan Cantt.
Ph: 0333-5349158

Gilgit:
House No.1, Gulsher Colony,
Eidgha Road,Konodas,
Near Sakarkovi,Opposite Amphary,Gilgit.
Ph/Fax: 05811-920687

__________________
''Sufficient for us is Allah , and He is the best Disposer of affairs" Al-Quran

Jazak'Allah for detailed answer. I emailed them as given in their contacts but email is not delivering and saying that Recepint email Quota is full. So I have to contact them on phone now.