Once a state ratifies a proposed amendment

Article five of the US constitution deals with the process of altering of the constitution and its ratification Both Congress and Senate can propose the Amendment. If the congress is about to submit a representation then it need two thirds vote in both the house of representatives and the senate . It can also be amended by convention of the states called by two thirds of the state legislatures. If the legislatures of the three-quarters of the states or the state ratifying conventions in three-quarters of the states ratifies the amendment, it becomes the part of the constitution and a copy of it send to the federal register for drafting a formal proclamation for the archivist to certify that the amendment is valid and has become part of the constitution. Then this certification is published in the federal register. After that US  statutes serves an official notice to the congress and to the nation that the amendment process had been completed.

If only one state ratifies a proposed amendment the it is of no use and cannot amend the constitution.

"the royal proclamation of 1763"