Let's understand why would you need an Appraisal Letter, You would need it as a proof to your new designation and the salary hike.
Are there email communications mentioning the appraisal? Does you new designation reflect along with your employee id in the ERP? How much have the hike changed your salary? Would you salary slip or even bank statement reflect that?
I suggest you collect the supporting documents and present it to your prospective employer. Please don't get into a case while exiting a firm. You need a clean comment from them in your back ground verification.
Please correct me in case I am wrong in my understanding. Looking forward to discuss this problem further with you.
4th June 2016 From India, Mumbai
2.) Second way, a kind of risky too, can I make a self edited appraisal letter? Is it verified by the company?""
When did the company conduct appraisal for you?
Your two suggestions are impractical and creating a fake appraisal letter will go against you.
Talk to the management and see about appraisal.
5th June 2016 From India, Pune