Flipkart blocks or suspends accounts of sellers if there are too many returns or if it suspects seller of malpractice. In that case, you will have to go to the seller dashboard of your account if you can access it or go to Flipkart seller page and support line. Raise a ticket through the seller support ticket dashboard. You can, of course, phone them on 1800 208 9898 but talking will not get you far. You will need to submit justifications or grounds to explain away the reason why they blocked your account. If they think it is OK the suspension is lifted after a month.
Talk to their rep on 1800 208 9898. They will check why your account was blocked and ask you for an explanation. Give them a detailed one, possibly by phone and by email. Then, if they accept the explanation your suspension may be revoked and you can get back to selling.
Most probably Flipkart had a good reason to suspend your account. It happens if you violate their policies. Did they tell you why they suspended your account? Email them at email@example.com or send SMS with text SELL(email iD) to 56677. They will get in touch with you. Better still, leave the whole matter to someone like Digicommerce to sort out.