Even some more basic Sinhala

I'm hungry = mata badaginiy

I'm thirsthy = mata thibahai

Thankyou (very much) = (bohoma) sthuthi

I don't want it = mata epa

Come (quickly) = (ikmanata) enna

Go (away) = (arahe) yanna

Doesn't matter = kamak naa

No problem (at all) = (kisima) prashnayak naa / awulak naa

I have no money (to give you) = (oyata denna) mata salli naa

I expect (you will come to meet me) =  mama balaaporoththu wenava (mama hamba wenna oya enava) kiyala
Who's is this wallet? = wallet eka kaageda?

What on earth are you doing! = oya monava karanavada manda!

Give (me) a loaf of bread = (mata) paan gediyak denna [mata is optional]

Give (me) five coconuts = (mata) pol gedi pahak denna [mata is optional]

I don't know English / I can't speak English = mata ingrisi baa

I don't know (How to speak English) = mama (ingris walin katha karanna) danne naa

Sarala Sms ekak liyanna podi Sinhala Vakya keepayak

(Some small Sinhala sentences to write a simple sms)

(1) Kohomada. (2) Mama hodin (innava). (3) oya(la)wa nethuva mata godak paalui. (4) oyage paula kattiya hodin innavada? (5) mama asai oya(la) ayith hamba wenna. c u.

(1) How are you?

(2) I am fine (innawa gives the sense of now, but to make a sms short best to drop it).

(3) I really miss you (oyalawa = you plural, more than one person). Lit: With you I am really despairing.

(4) Are your family members well?

(5) I like to meet you (oyala = you plural) again.

some more stuff

sound's good = niyamai wage, maru wage
I didn't get that = mata eka therune naha.(= I didn't understand that)
obviously = aththenma/nisakawama
please = karunaakarala
sorry = samaawenna.
Please excuse me = Karunakarala mata samaawennna.
give me a minute = mata winaadiyak denna
leave me alone = mata paaduwe inna denna/mata thaniyama inna denna
I like that. = mama ekata kamathiy
I want that/I need that = mata eka onaa/mata eka awashyayi
just in time = welaawatama awaa
ex:
You came here just in time-Oba(in spoken-oyaa) welaawatama methanata awaa.

I hope so = mama hithanawa ehemai kiyala
is that so = aa ehemada

Correct me if i made any mistake in English. But I hope I did it well.

Sinhala Basic

Good morning! = suba udaesanak wewa
Good evening! = suba sandyawak wewa
Good night! = suba raathriyak wewa
Nice to meet you! = oba munagesima sathutak
Happy birthday!= suba upandinak wewa 
Happy new year! = suba aluth auruddak wewa
Merry Christmas! = suba naththalak wewa
Congratulations! = suba pathum

Good luck = wasanawantha wewa
I Don't Understand!= mata therenne naha / wetahenne naa / "therunaaa" 
I Don't Know!= mama danne ne

No idea! = ane manda
What Is This? = me mokakda
Don't worry! = karadara wenna eoa
Really! = aththada?

See you later = gihin ennam

come off it! = boru kiyanna epa

cool! = ela