I am 48 y old I lost my job last 6 month ,I have 18yr experience in korean mnc company in purchase department,now I want to start our bussiness ,pls let me know how to I start bussiness

Ans: First, assess your current situation overall - personal and professional and be sure that own business is the most viable/ sensible option.
Then, make a list of ideas that resonate strongly with you, refine it, do some initial validation and shortlist on the final 1/2 that are most appealing.
Figure out the finances required, personal (for the family) and for the business. Ensure that it will not create issues that can derail you.
Time now for more on the ground market research including prospective users/buyers, assessing competition/ alternatives, checking with suppliers, regulatory environment etc.
Make an initial business plan with key assumptions clearly spelt out and validated as much as possible. Also see if you want to have partners/ co-founders who share this vision and have complementary skills/ experience.
See if you can make an initial prototype of your offering (MVP minimum viable product) and again test it with your potential customers; iterate to see what changes are required including revenue models, go to market approaches etc.
Now is the time to formally register your business - single person company, LLP etc. Get professional expertise as required.
Revisit your Business plan and change as required.
Formally launch, test market, make changes and then go full steam ahead

All the best.