I took my phone to repair center for water damage and nothing happened

Most repair shops won't even work on water damaged phones because once they are wet they can still corrode over time. The only reason they will work on phones is to retrieve data and photos. I would take it to another shop and get the data out of it but if you don't want any data or pictures I would buy another phone.

Personally, if it was my phone - and a gift from my dad - I'd take the chance on replacing the screen. I don't know how much it will cost you in the Philippines, but here in the US they're fairly inexpensive; I just looked one up on another question and found it for about $24 USD on Amazon after a very cursory search.

Amazon.com: for Samsung A21s Screen Replacement kit for Samsung Galaxy a21s a217 Screen Replacement 2020 SM-A217M/DS LCD Display Touch Digitizer Assembly 6.5 Inch (A21S with Frame) : Cell Phones & Accessories

There are a couple of reasons for my thinking. First, your quick action it taking it to a repair shop immediately was a good call; assuming they did a good job of flushing the water out hopefully they saved it from further damage, at least as much as possible. Secondly, if it's still working next month when you're ready to replace the screen, that's a good indicator that it may well continue to work in the future.

The fact that the screen failed immediately is not surprising; it's very common for screens to die when exposed to liquids. One other item you might consider is the battery; usually it's recommended that the battery be replaced whenever it's been exposed to liquid.

Good luck; let us know what you decide and how it all turns out for you!