I advise you to first apply for Anticipatory bail under s. 438 of CrPC so that the police may not arrest you and subject you to harassment and torture.

After getting bail you can approch High Court under s.482 to quash the FIR as the allegations against you are in your absence/retirement from service. For a case of prevention of corruption act it most essential to recover the bribe amount. Which in your case has not happened. 

The police has no power to compel you to give voice sample as it amounts to self incrimination and violation of fundamental rights guaranteed under Indian Constitution..

The Application can be filed by a person under Sec 482 of Crpc to the High court for getting the frivolous FIR filed against him quashed.. 

Laws regarding electronic record and their admissibility are properly laid down in Section 65B of Indian Evidence Act. The contents of electronic records may be proved in accordance with the provisions of section 65B. Therefore, in order to understand whether a voice recording can be used as an evidence in courts in India, an understanding of section 65B of Indian Evidence Act is necessary..

Dear Client,

After retirement no sanction require to submit cahrge sheet and law is clear that sanction to prosecute the public servant for the offenses under the POC Act is not required if the public servant had already retired on the date of cognizance by the court. However the sanction is required for offenses under IPC. Unlike section 19 of the POC Act, the protection under section 197 of Cr.P.C. is available to the concerned public servant even after retirement.

If charge sheet filed, you will be arrested.

Demand and acceptance of gratification must be proved for an offense under s.7 and here when police trap failed , it changed the whole case by changing nature of offense from sec 7 to u/s 8 and 9 of act.

Is there any allegation, that you are ask for bribe for some person govt. servant or will work done under your influence ?

And court order is mandatory for taking voice sample, court will not rely on sample.

Dear Sir,

(1) can they file the charge sheet against me in the court of law as I was not a govt servant when the FIR was lodged

Ans: Yes, charge sheet can be filed against private persons also but you have to challenge the before the High Court or file discharge application before the trial court.

(2) Do ACB have a power to take action against me as I was not a govt servant, at the time of filing of FIR, no work of the complainant was pending with me and I have not accepted the bribe amount.

Ans: They will create some evidence and make believe story.

(3) Do they have the power to arrest me before filing the charge sheet.

Ans: yes, it is better get anticipatory bail.

(4) Can the FIR be quashed in the High court of Karnataka.

Ans: Yes, you can try for it.

can the ACB file charge sheet without sanction from the govt as iam no more a govt servant at the time of filing of FIR and the pc act applies only to the govt servant ?

Ans: If you are govt. servant as on the date of incident then only sanction is necessary.

can sec 8 & 9 of PC Act 1988 applies to me in the present case? can the FIR be quashed?

Ans: Yes, first immediately approach the High Court and get stay on the investigation

Yes as far as the above things are concerned you can go for quashing before HC as the said case has many lacunas

1. They can file the charge sheet on the basis of the investigation carried out in the FIR before them.

2. Since the incident is related to the period of your tenure in your office, they may proceed.

3.  If there is a FIR registered, they can arrest  you and remand you to judicial custody.

4. You can file a petition under section 482 cr.p.c. and present strong arguments.

Yes, they can very well proceed without seeking sanction for the arrest against the retired employee.