Hi @Sathappan Nagappan
Call the repairer back as they should have checked that all was working properly before they left after completion of the work.
If they're not obliging or want to charge for this then you'll have to open up the washer yourself and check.
The repairman may have disconnected the internal hoses before they connect to the inlet solenoids to get better access etc to install the water softener and may not have reconnected a hose correctly.
What is the make and model number of the washer?