you are not doing the valuation

the engineer does it.

so talk to the engineer or in a consultancy (there are tons around find them). they will need your passport, all lalpurja, and tax slips and they will evaluate your properties based on current values. you may also need relation certificates of your family and yo your uncle.

once you are done with this take this evaluation along with other sources of income and deposits to the CA and he/she will certify your total income, assets and savings

hope that helps

My suggestion:

Don't put too much effort into this, Besides the I-20 and other essential documents, The consulars won't verify any information you provide. If they have any doubt about anything they will just deny your application. Anyways they take less than a minute to interview. Long time ago mine was mere 30-40 seconds.

Make a letter from your father or uncle that they will support your studies.

Property evaluation can be done at Municipality / VDC where your land, house etc is located. There will be consulting engineer who do this. You can request them to valuate more than actual is ! They take some percent (as Municipality rule eg. 0.1% etc) for doing this.