I talked a lot with Buyer and he suddenly went offline. Shall I wait for him now or not?
Yes, wait. Probably they have lost interest and isn’t professional enough to say. People are rather cruel like that. You can try asking in a few days if you can still assist them in this but chances are you will never hear from them again.
I do hope that you didn’t give them all the info on how to do the job as if so you have just been pumped & dumped. Learn not to give away the farm before you get paid.
Of course, you should wait for the buyer. Click him within a day or two. If he is willing to get your services, he will respond, otherwise not.
All he best